HomeMy WebLinkAboutR-9584 Water and Wastewater Management Element of General Plan - Amending Certain PoliciesN
RESOLU'T'ION NO. 9584 (2004 Series)
A RESOLUTION OF THE COUNCIL OF THE CITY OF SAN LUIS OBISPO
AMENDING CERTAIN POLICIES IN THE WATER AND WASTEWATER
MANAGEMENT ELEMENT OF THE GENERAL PLAN
WHEREAS, the San Luis Obispo County Flood Control and Water Conservation
District (County) owns an entitlement to 17,500 acre -feet per year (afy) of water from
Nacimiento Reservoir; and
WHEREAS, the County has solicited participation in a pipeline project to deliver
Nacimiento water to cities and other water purveyors in the County (Project); and
WHEREAS, the City has submitted a request to the County for 3,380 afy of water from the
Nacimiento Project; and
WHEREAS, a review of policies contained in the Water and Wastewater Management
Element to the General Plan identified certain amendments that are needed in order to maintain
consistency with the requested allocation of water from the Nacimiento Project; and
WHEREAS, the proposed policy amendments are viewed as strengthening the City's
overall water supply planning policies, regardless of any particular new water supply opportunity, in
that they further define our water supply management strategies and objectives with a particular
focus on reliability; and
WHEREAS, the proposed policy amendments also strengthen the tie between the General
Plan and water supply availability, providing assurance that new supplies do not induce growth
beyond that envisioned in the General Plan.
WHEREAS, the City Council finds that the proposed amendments to the Water and
Wastewater Management Element are consistent with the goals and policies of the General Plan,
the purposes of the Zoning Regulations and other applicable City ordinances.
BE IT RESOLVED by the Council of the City of San Luis Obispo hereby approves:
SECTION 1. Environmental Determination. The City Council finds and determines that
the Negative Declaration recommended by the City's Community Development Department
adequately addresses the potential environmental impacts of these General Plan amendments,
and reflects the independent judgment of the City Council. The Council determines that the
amendments will have no significant effects on the environment. The Council hereby adopts said
Negative Declaration.
R 9584
Resolution No. 9584 (2004 Series)
Page 2
SECTION 2. Policy 3.1.5 is added to reflect the understanding that water demand is
variable with the seasons and it is necessary for the City to meet the peak daily demands of the
community, as well as the annual average needs, in order to provide reliable service to our
customers. Specific language is included in the legislative draft of the Water and Wastewater
Management Element, which is attached hereto and marked as Exhibit A.
SECTION 3. Policy 5.1.1 is amended to provide for the accounting of siltation at the
City's water supply reservoirs over a longer term when considering new water supply
opportunities (Exhibit A).
SECTION 4. Policy 6.1.1 is amended to include planning for two levels of supplemental
water supply requirements and the development of supplemental water supplies (Exhibit A).
SECTION 5. Policy 7.1.1 is amended to include language that identifies the need to
provide for peak operating demands, in the event that one of our major supply sources is
unavailable, as a goal and benefit of multi - source water supply development (Exhibit A).
SECTION 6. Policy 8.1.1 is amended to include priority for allocation of new water
supplies (Exhibit A)..
SECTION 7. Policy 8.1.2 is amended to establish the method for determining the
amount of water that is available for allocation to new development (Exhibit A).
Upon motion of Council Member Settle, seconded by Council Member Ewan,
and on the following roll call vote:
AYES: Council Members Ewan and Settle, Vice Mayor Schwartz and
Mayor Romero
NOES: Council Member Mulholland
ABSENT: None
P
Resolution No. 9584 (2004 Series)
Page 3
The foregoing resolution was adopted this 29`h day of June, 2004.
Mayor David F. Romero
ATTEST:
Diane Reynol s, OM.C.
Deputy City Cle
APPROVED AS TO FORM:
i
Jonah . Lowell
City Attorney
City of San Luis Obispo
General Plan
Water & Wastewater Management Element
Exhibit A
This element was first adopted February 24, 1987, by City Council Resolution No. 6180A. The
following amendments have been adopted:
Topic
Wastewater section added
Revised water section
Water offset potential for annexations,
accounting for reclaimed water, and use
of wells
Clarifying water allocation to develop-
ment, required offsets, and use of wells
Accounting for siltation and correcting
safe yield information
Reliability reserve, offsets, siltation, and
reclaimed water
Date Council. Resolution Number
October 26, 1987 6351
November 15, 1994
July 2, 1996
December 13, 1999
May 16, 2000
September 3, 2002
8370
8560
9003
9044
9363
Exhibit A
The City s General Plan is made up of sections called "elements." Each element focuses on certain
topics as required or allowed by State law. According to State law, each element has equal weight in
defining City policies. In September 2002, the following elements comprised the Citys General Plan.
'Update in progress.
Revn ion _Date
Land Use
1994
Housin •
1994
Circulation
1994
Open Space
1994
Conservation'
1973
Parks & Recreation
2001
Noise
1996
Safety
2000
Energy Conservation"
1981
Water & Wastewater Management
1996
'Update in progress.
Exhibit A
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
CONTENTS
INTRODUCTION......................................................................................... ............................... 1
WATER SECTION
1.
Safe Annual Yield ................................................................................ ............................... 2
2.
Water Conservation ............................................................................. ...............................
5
3.
Water Demand Projections ................................................................. ...............................
6
4.
[reserved section number]
5.
Siltation at Salinas and Whale Rock Reservoirs ................................... ...............................
9
6.
Supplemental Water Requirements .................................................... ...............................
10
7.
Multi- source Water Supply ............................................................... ...............................
12
8.
Allocation of New Water Supplies .................................................... ...............................
12
9.
Water Allocation and Offsets ............................................................... .............................14
10.
Reclaimed Water ............................................................................. ...............................
15
11.
Water Service within the City ........................................................... .......:.......................
16
WASTEWATER SECTION
12. Service Area and Population ............................................................. ............................... 17
13. Wastewater Collection, Treatment, and Disposal ............................... ............................... 19
14. Wastewater Revenues and Financing ................................................ ............................... 20
TABLES
NUMBER TITLE Page
1 Safe Annual Yield ................................................................. ............................... 3
2 Water Use 1980 - 1999 ............................................................ ............................... 7
3 Per Capita Water Use .............................................................. ............................... 8
4 Calculation of Present (2002) Water Demand ........................ ............................... 8
5 Salinas Reservoir Capacity Studies ...................................... ............................... 10
6 Required Safe Annual Yield for General Plan Build- out ....... ............................... 11
7 New Water Supply Requirements ........................................... .............................11
Exhibit A
C
City of SLO General Plan Water & Wastewater Management Element
INTRODUCTION
The City's General Plan guides the use and protection of various resources to meet community
purposes. It reflects consensus and compromise among a wide diversity of citizens' preferences,
within a framework set by State law... The General Plan contains elements that address various
topics.
The City decided to adopt an element addressing water resources and wastewater treatment because
of the vital role of these resources and the far- reaching impacts of water policies on community
growth and character. This element translates the Land Use Element's capacity for development into
potential demand for water supply and wastewater treatment. This element outlines how the City
plans to provide adequate water and wastewater services for its citizens, consistent with the goals
and policies of other General Plan elements.
Before adopting or revising any General Plan element, the Planning Commission and the City
Council must hold public hearings. The City publishes notices in the local newspaper to let citizens
know about the hearings at least ten days before they are held. Also, the City prepares environmental
documents to help citizens understand the expected consequences of its planning policies before the
hearings are held.
Anyone may suggest or apply for amendments to General Plan elements. The City will probably
update this element about every five years, or more frequently if necessary.
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
WATER SECTION
1.0 SAFE ANNUAL YIELD
1.1 POLICIES
1.1.1 Basis for Planning
The City will plan for future development and for water supplies based on the amount of water
which can be supplied each year, under critical drought conditions. This amount, called "safe annual
yield," will be formally adopted by the Council. The safe annual yield determination will be revised
as significant new information becomes available, and as water sources are gained or lost. The
determination will consider a staff analysis, which will recommend an amount based on coordinated
use of all water sources. Each change to safe annual yield will be reflected in an amendment of this
Plan.
1.1.2 Safe Yield Amount
The City's safe annual yield, from the coordinated operation of Salinas and Whale Rock reservoirs.
and 500 acre feet of groundwater, is shown in Table 1. The safe annual yield includes reductions due
to siltation at the reservoirs, discussed in more detail in Section 5.0.
1.1.3 Groundwater
A. The amount of groundwater which the City will rely upon towards safe annual yield is
identified in policy 1.1.2. The City will maximize the use of groundwater in conjunction
with other available water supplies to maximize the yield and long -term reliability of all
water resources and to minimize overall costs for meeting urban water demands. The City
shall monitor water levels at the well sites to determine whether reduction or cessation of
pumping is appropriate when water levels approach historic low levels.
B. The City will not compete with local agricultural use of groundwater outside the urban
reserve line or damage wildlife habitat through reduced natural stream flows in obtaining
long -term sources of water supply.
BACKGROUND
Safe annual yield is the amount of water that can reliably be produced by the City's water supply to
meet the water demand. It is estimated by simulating the operation of the City's water supply sources
over an historical period to determine the maximum level of demand that could be met during the
most severe drought for which records are available.
The safe annual yield of an individual source of water supply is defined as the quantity of water
which can be withdrawn every year, under critical drought conditions. Safe annual yield analyses of
water supply sources are based on rainfall, evaporation and stream flow experienced during an
2
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
historical period. The City of San Luis Obispo uses a period beginning in 1943, which covers
drought periods in 1946 - 51,1959- 61,1976 -77, and 1986 -91. The historical period used in the latest
computer analysis to determine safe annual yield extends from 1943 through 1991 and includes the
most recent drought. Although future conditions are unlikely to occur in the precise sequence and
magnitudes as have occurred historically, this technique provides a reliable estimate of the future
water supply capability of the existing sources, since the long term historical record is considered a
good indicator of future conditions.
The safe annual yield gradually declines as silt accumulates in the reservoirs, thereby reducing
storage capacity (discussed in more detail on page 10).
Prior to 1991, the "controlling drought period" for determining safe annual yield was 1946 to 1951.
The critical period for determining safe annual yield from the two reservoirs is now the period from
1986 to 1991. The safe annual yield is reflected in the table below and includes estimated losses
associated with siltation.
TABLE 1
SAFE ANNUAL YIELD
Year
Salinas & Whale
Rock Reservoirs
Groundwater
Total
2000
7,040 acre feet
500 acre feet
7,540 acre feet
2001
7,030 acre feet
500 acre feet
7,530 acre feet
2002
7,020 acre feet
500 acre feet
7,520 acre feet
2003
7,010 acre feet
500 acre feet
7,510 acre feet
2004
7,000 acre feet
500 acre feet
7,500 acre feet
2005
6,990 acre feet
500 acre feet
7,490 acre feet
2006
6,980 acre feet
500 acre feet
7,480 acre feet
2007
6,970 acre feet
500 acre feet
7,470 acre feet
2008
6,960 acre feet
500 acre feet
7,460 acre feet
2009
6,950 acre feet
500 acre feet
7,450 acre feet
Previous Safe Annual Yield Studies
Previous studies of the critical historical drought periods at Salinas and Whale Rock reservoirs have
indicated the following safe annual yields were available to the City:
Water Sunnly
Safe Annual Yield
Reference
Salinas Reservoir
4,800 acre-feet
Corps of Engineers, 1977
Whale Rock Reservoir*
2,060 acre-feet
Dept Water Resources, 1974
Coordinated Operation
500 acre -feet
CH2M -Hill, 1985
Groundwater
500 acre-feet
Water Operational Plan, 1993
TOTAL
7,860 acre -feet
*City's share of Whale Rock Reservoir safe annual yield.
3
Exhibit A
C,
City of SLO General Plan Water & Wastewater Management Element
Past safe annual yield analyses for the two reservoirs assumed independent operation and historical
data to the date of each report. The critical drought period for the previous studies was 1946 -51.
The studies also assumed a minimum pool at Salinas and Whale Rock of 400 and 500 acre -feet
respectively. "Coordinated operation" is a concerted effort to operate the two reservoirs together for
maximum yield. Since Salinas Reservoir spills more often than Whale Rock Reservoir, due to its
larger drainage area and more favorable runoff characteristics, and has higher evaporation rates, the
combined yield from the two reservoirs can be increased by first using Salinas to meet the City's
demand and then using Whale Rock as a backup source during periods when Salinas is below
minimum pool or unable to meet all of the demand. The 500 acre -feet increase in safe annual yield
was a preliminary -estimate of the additional yield attributed to coordinated operations of the
reservoirs identified in the 1985 report prepared by CH2M -Hill.
In 1988, the City contracted with the engineering firm of Leedshill - Herkenhoff, Inc., to prepare a
detailed analysis of the City's water supplies and safe annual yield, based on coordinated operation of
the reservoirs. The report "Coordinated Operations Study for Salinas and Whale Rock Reservoirs"
was completed in 1989. The study estimated total safe annual yield for the City from the two
reservoirs to be 9,080 acre -feet per year. Since the study period was only to 1988 and the City was in
a drought period of unknown length, this amount was never adopted by Council. It should be
emphasized that this estimate assumed that the "controlling drought period" was 1946 to 1951 and
that Whale Rock Reservoir is used only when Salinas is below minimum pool or can not meet the
monthly City demand, and does not consider limitations on the use of Salinas water due to water
quality constraints. Following the end of the 1986 -1991 drought, staff updated the computer program
created by Leedshill- Herkenhoff to estimate the impact of the drought on safe annual yield of the
reservoirs. The analysis determined that the recent drought was the critical drought of record for the
two reservoirs and resulted in a reduction in the safe annual yield.
Groundwater Resources
The groundwater basin that underlies the City of San Luis Obispo is relatively small. Therefore,
extractions in excess of 500 acre -feet per year during extended drought periods cannot be relied
upon. Because the basin is small, it tends to fully recharge following significant rainfall periods.
Following periods of above average rainfall, the groundwater basin may be capable of sustaining
increased extraction rates to meet City water demands. Since both Salinas Reservoir and the
groundwater basin fill up and "spill" following significant rain periods, there is a benefit in drawing
from these.sources first and leaving Whale Rock Reservoir as a backup supply. The conjunctive use
of the groundwater basin and surface water supplies in this manner will provide an effective
management strategy that increases the reliability of all the resources to meet current and future
water demands.
Another benefit of maximizing groundwater use is that it typically requires minimal treatment that
reduces costs compared to surface water supplies. Even with treatment for nitrates and PCE, the
projected costs associated with that treatment show groundwater to be comparable to other
alternative future water supply projects.
Past City policy has been not to compete with agriculture for use of groundwater resources.
Recognizing the importance of the production of food and fiber as well as open space provided by
agricultural land outside the urban reserve line, the City will continue to endorse this policy.
4
Exhibit A.
n
City of SLO General Plan Water & Wastewater Management Element
2.0 WATER CONSERVATION
2.1 POLICIES
2.1.1 Long -term Water Efficiency
The City will implement water - efficiency programs which will maintain long -term, per- capita usage
at or below the per capita use rate as identified in Policy 3.1.2.
2.1.2 Short -term Water Shortages
Short-term mandatory measures, in addition to the long -term programs, will be implemented when
the City's water supplies are projected to last three years or less based on projected water
consumption, coordinated use of all city water supply sources, and considering the drought pattern
on which safe yield is based (or response to other situations which may interrupt supply).
BACKGROUND
Water conservation was referenced as a part of the City's water management policy in 1973. In 1985,
the City adopted the Annual Water Operational Plan policy that established water conservation as a
means of extending water supplies during projected water shortages. Since 1985, many
technological and philosophical changes have occurred which are proving water conservation to be
both a short term corrective measure for immediate water supply shortages and a long term solution
to water supply reliability.
A comprehensive evaluation of the potential water savings from current water conservation
technologies and programs is included as Appendix V to this Plan. Based on the reliability of the
water conservation measures which were evaluated, and the cost effectiveness of the proposed
programs, a long term reduction in water demand of approximately twenty percent from the average
per capita use recorded in 1986 -87 is used for planning for future water conservation programs as
well as future water supply needs.
Because of the experience during the drought of 1986 to 1991, the City has developed a short term
plan to deal with immediate water shortages and has recognized the importance of water efficiency
by supporting long term programs. The City will reevaluate and update its water conservation efforts
in response to changing water demand, supplies, technology and economic conditions.
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
3.0 WATER DEMAND PROJECTIONS
3.1. POLICIES
3.1.1 Basis of Projections
The City will project water requirements, considering long -term conditions and the full range of
water uses in the City.
3.1.2 Water Use Rate
The City shall use 145 gallons per person per day (this equates to approximately 0. 162 acre-foot per
person per year) and the number of City residents to plan total projected future water demand. This
quantity will be revised if warranted by long -term water use trends, including differences in the
relationship between residential and nonresidential usage. (Throughout this Plan, 145 gallons per
person per day is used in computations of future water demand.)
3.1.3 Overall Projected. Demand
Applying 145 gallons per person per day to a projected City resident population of about 56,000 at
General Plan build -out results in a projected water demand of 9,096 acre-feet per year (excluding
demand from the Cal Poly campus, which has separate entitlements).
3.1.4 Present Water Demand
Present water demand shall be calculated by multiplying the water use identified in Policy 3.1.2 by
the current city population (as determined by the California Department of Finance, Population
Research Unit).
3.15 Peak Daily Water Demand
stri
BACKGROUND
The City must know how much water will be needed to serve residents, businesses, and other users
to accommodate the General Plan. This quantity can be projected using different methods. All
methods involve assumptions about both future usage rates and the numbers and types of users
expected in the future. The quantity expressed in the policy above corresponds closely with both (1)
total city-wide usage compared with total resident population and (2) projections of water demand
based on usage by various land use categories. There always will be some uncertainty in estimating
development capacity (such as the number of dwellings or residents) as well as the usage per
customer type (such as acre-feet per dwelling or per resident.) The estimating method must use
reasonable assumptions, based on experience, to assure an adequate level of water supply while not
overstating demands.
Since the early 1970's, usage estimates have ranged from 0.17 to 0.22 acre -foot per resident per year
(about 155 to about 195 gallons per person per day). The estimates have varied so widely due to
31
Exhibit A
U
City of SLO General Plan Water & Wastewater Management Element
actual differences in consumption over time and to confusion about accounting for Cal Poly usage.
(The City treats and delivers much of the water used by Cal Poly, even though Cal Poly has separate
entitlements.) Table 2 shows recent water usage compared with City resident population. Table 3
compares the "per capita" and "land use" methods of estimating water needs.
TABLE 2
WATER USE 1980 -1999
Year
Water from Treat-
ment Plant and Wells
acre -feet (1)
Total City Water
Demand
acre-feet (2)
Population
(3)
Total Gallons
per Person per
Day
City Gallons
per Person
per Day
1980
6,745
6,145
34,252
176
160
1981 1
6,941
6,341
34,759
178
163
1982
6,584
5,984
35,239
167
152
1983
6,800
6,200
35,660
169
155
1984
7,862
7,262
36,407
182
178
1985
8,025
7,425
37,378
193
177
1986
1 8,367
7,767
38,205
196
181
1987
8,399
7,799
38,282
196
182
1988
8,411
7,811
39,858
188
175
1989
6 004
5 404
41,027
129
118
1990
4 796
4196
41958
102
89
1991
4 640
4 040
42178
98
86
1992
5,316
4,716
42,922
110
98
1993
5,572
4,972
43,415
115
102
1994
5,775
5,200
43,919
117
106
1995
6,075
5,574
41,295
131
120
1996
6,379
5,742
41,404
138
125
1997
6,868
6,220
41,807
147
133
1998
6,399
5,852
42,201
135
124
1999
6,736
6,172
1 42,446
1 142
129
Bold, italicized years (1989 - 1991) indicate mandatory conservation period.
(1) Data from City Water Treatment Plant production reports; includes Cal Poly potable water.
(2) Cal Poly water use assumed constant for years before 1994, at 600 acre-feet.
(3) January 1 population estimates from the California Department of Finance, Population Research Unit, as
revised through 1999.
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
TABLE 3
PER CAPITA WATER USE
Method 1: Water treatment plant production and
Method 2: Metered use by development type
Population
and Land Use Element
Per capita water use - based on historic demand,
Per capita water use - based on historic
population, and conservation
demand, land use, and conservation
Annual demand 1987 year highest use
8,397 acre -feet
General Plan build -out (1992 draft)
Land use types (with 20% reduction from pre-1987
1 acre -foot
Less Cal Poly Subtract 600 acre -feet
7,797 acre -feet
usage ram)
from total, based on average demand
325,851 gallons
Single family residential 3,630 acre -feet
7,216 acre feet
Multifamily residential 2,633
Retail commercial 422
Office 393
Per capita use Convert to gallons and
182 gallonstday,
Services & manufacturing 438
divided by 365. Divide by Dept. of finance
Motel/hotel 608
population estimate (38,282)
Hospitals, schools, parks 1,432
Total 9,566 acre -feet
Less 20% long -term conservation
145 gallons/day
Per capita use Convert to gallons
152 gallons/day
and divide by 365. Divide by estimated
56,000 build-out population (excludes
Cal Poly residents).
Based on the analysis of these two approaches and the inclusion of long term water conservation
programs, 145 gallons per day per person is used throughout this element for long term water supply
planning purposes.
TABLE 4
CALCULATION OF PRESENT (2002) WATER DEMAND
Gallons per
City
Gallons per
Days in
person per day
Population
Acre Foot
a Year
Current Demand
1 acre -foot
145
44,426
325,851 gallons
365
7,216 acre feet
4.0 [Contents of Section 4.0 deleted by September 2002 amendment. Numbering of following
sections retained to avoid confusion in references among documents.]
E
Exhibit A
City of SLO General Plan Water & Wastewater_ Management Element
5.0 SILTATION AT SALINAS AND WHALE ROCK RESERVOIRS
5.1 POLICY
5.1.1 Accounting for Siltation
The City shall account for siltation in the adoption of the safe annual yield as identified in Policy
1.1.2. The estimated annual reduction in safe annual yield from Salinas and Whale Rock Reservoirs
is 10 acre -feet per year
BACKGROUND
Siltation at reservoirs is a natural occurrence that can substantially reduce the storage capacity over
long periods. The reduction of available storage will reduce the safe annual yield of the reservoirs.
Siltation at reservoirs varies depending on factors such as rainfall intensity and watershed
management practices. There have been numerous reports addressing siltation at Salinas Reservoir,
but no studies have been done for Whale Rock Reservoir.
Table 5 lists the studies for Salinas Reservoir and the estimated storage capacities. During the recent
drought, water at Salinas Reservoir fell to record low levels. Recognizing the unique opportunity
presented by the low water level, the County contracted with a local engineering consultant to
provide an aerial survey of the lake and prepare revised storage capacity information. The latest
information reveals that the survey conducted in 1975 may have over estimated the siltation rate at
the reservoir. Early studies indicated average annual siltation rates from 23 acre -feet per year to 34
acre -feet per year. The study done by the U.S. Geological Survey in 1975 estimated that the siltation
rate was approximately 82 acre-feet per year. The latest information indicates that the siltation rate is
on the order of 40 acre -feet per year.
Since Whale Rock is used as a backup supply for the City, it may be many years until the lake level
drops to the point where an aerial survey of siltation can be economically performed. Since no
information is available to indicate what rate of siltation is occurring at the Whale Rock Reservoir, it
is assumed for planning that the annual average rate of siltation is similar to Salinas Reservoir. -Pe
New water supply
opportunities can be utilized to offset the long term siltation losses, as discussed elsewhere in this
document.
The safe annual yield from the two reservoirs will be continually reduced as a result of siltation. The
City's computer model can be used to calculate the reduction in safe annual yield from Salinas and
Whale Rock reservoirs to date. The model can then be used to calculate estimated annual reductions
in the future assuming siltation occurs in an average pattern.
Since the storage capacity for Salinas Reservoir was last estimated in 1990, the annual loss of 40
acre -feet per year can be applied from that date. However, since siltation at Whale Rock Reservoir
has never been factored into the total available water storage, the loss of 40 acre -feet per year would
apply to the period since the reservoir was constructed in 1961.
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
TABLE 5
SALINAS RESERVOIR CAPACITY STUDIES
The estimated loss in storage capacity for Salinas Reservoir between 1990 and 2000 is 400 acre -feet.
The estimated loss at Whale Rock Reservoir between 1961 and 2000 is 1,560 acre -feet. Based on
these reduced storage capacities, the computer model projects a loss of 250 acre-feet of safe annual
yield from the combined operation of the two lakes. With an estimated loss of 40 acre-feet per year
at each reservoir, the total safe annual yield from the two lakes will be reduced by 10 acre-feet per
year. This loss of yield is accounted for in the adopted safe annual yield figures shown in Table 1.
6.0 SUPPLEMENTAL WATER REQUIREMENTS
6.1 POLICIES
6.1.1 Supplemental Water Requirement
The City shall develop additional water supplies to
/ '._J_ Tl__ /T_L1_ L\ -_A r-
.provide for the Primary Supply Requirements
identified below, and strive to develop additional water supplies to provide for the Secondary Supper
Requirements identified below, in the consideration of available water supply opportunities.
1. Primary Supply Requirements — Develop supplemental water supplies to provide sufficient
water for General Plan build -out using the ver- capita planning use rate identified in Policy 3.1.2
multiplied by the projected General Plan build -out population, and
10
Total
Usable
Avg Annual Loss
Year
Agency
Capacity
Capacity
Usable Capacity
(acre -feet)
(acre -feet)
(acre - feet/year)
1941
U.S. Army
44,800
26,000
-
1947
U.S. Soil Conservation
-
25,860
23.3
Service- -
1953
U.S. Soil Conservation
Service and U.S. Forest
-
25,590
34.2
Service
1975
U.S. Geological Survey
41,400
23,200
82.4
1990
Coun of San Luis Obispo
41,791
24,035
40.1
Usable capacities are shown at the 1,301.0 -foot spillway elevation because the usable capacity at the 1,300.7 -
foot elevation for the 1947 and 1953 studies could not be accurately determined. Usable capacity at the
1,300.7 -foot elevation for the 1941 survey was determined to be 25,800 acre -feet and for the 1975 survey was
23,000 acre -feet.
The estimated loss in storage capacity for Salinas Reservoir between 1990 and 2000 is 400 acre -feet.
The estimated loss at Whale Rock Reservoir between 1961 and 2000 is 1,560 acre -feet. Based on
these reduced storage capacities, the computer model projects a loss of 250 acre-feet of safe annual
yield from the combined operation of the two lakes. With an estimated loss of 40 acre-feet per year
at each reservoir, the total safe annual yield from the two lakes will be reduced by 10 acre-feet per
year. This loss of yield is accounted for in the adopted safe annual yield figures shown in Table 1.
6.0 SUPPLEMENTAL WATER REQUIREMENTS
6.1 POLICIES
6.1.1 Supplemental Water Requirement
The City shall develop additional water supplies to
/ '._J_ Tl__ /T_L1_ L\ -_A r-
.provide for the Primary Supply Requirements
identified below, and strive to develop additional water supplies to provide for the Secondary Supper
Requirements identified below, in the consideration of available water supply opportunities.
1. Primary Supply Requirements — Develop supplemental water supplies to provide sufficient
water for General Plan build -out using the ver- capita planning use rate identified in Policy 3.1.2
multiplied by the projected General Plan build -out population, and
10
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
2. Secondary Supply Requirements — Develop supplemental water supplies to provide additional
yield to account for future siltation losses, drought contingency, loss of yield from an existing supply
source, operational requirements necessary to meet peak operating demands, and other unforeseen
conditions.
6.1.2 Supplemental Water Sources
In deciding appropriate sources of supplemental water, the City will evaluate impacts on other users
of the water and other environmental impacts, total and unit costs, reliability, water quality,
development time, and quantity available.
6.1.3 Paying for Supplemental Water for New Development
The cost for developing new water supplies necessary for new development will be paid by impact
fees set at a rate sufficient to cover the annual debt service cost of the new water supplies attributable
to new development.
BACKGROUND
Based on the Land Use Element adopted by the City Council in August 1994 and a per capita use
rate of 145 gallons per person per day, the projected total amount of water for the City to serve
General Plan build -out is 9,096 acre-feet. , siltatien
less, and the resulting supplemental water- requirement neeessary te meet pfejeeted City water-
Many of the Secondary Supply Requirements identified in Policy 6. 1.1 are unquantifrable at
this time, and their development should be considered by Council in the lit -review of new water
supply opportunities.
TABLE 6
REQUIRED SAFE ANNUAL YIELD
FOR GENERAI. PLAN BUILD -OUT
Source of Demand
Population
Acre -feet
(at 145 gal per
day r on)
Percent
of Total
Existing (2002) Development
44,426
7,216
79.3%
New Development
11,574
1 1,880
20.7%
TOTAL
56,000
9,096
100.0%
11
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
City policy adopted in 1987 as part of the Water Element states that the costs of developing
supplemental water sources will be borne by those making new connections to the water system.
Policy 6.1.3 continues this policy and is consistent with the Land Use Element (policy 1.13.4.)
7.0 MULTI- SOURCE WATER SUPPLY
7.1 POLICY
7.1.1 Multi- Source Water Supply
The City shall continue to develop and use water resources projects to maintain multi- source water
supplies, and in this manner, reduce reliance on any one source of water supply. -ate to Provide for
peak operating demands in the event one of the City's maior water supply sources is unavailable. and
to increase its supply options in future droughts or other water supply emergencies.
BACKGROUND
Having several sources of water can avoid dependence on one source that would not be available
during a drought or other water supply reduction or emergency. There maybe greater reliability and
flexibility if sources are of different types (such as surface water and ground water) and if the sources
of one type are in different locations (such as reservoirs in different watersheds).
The Water Element of the General Plan, adopted in 1987, identified multiple water projects to meet
projected short and long term water demand. In November of 1990, the Council again endorsed the
multi- source concept.
12
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
8.0 ALLOCATION OF NEW WATER SUPPLIES
8.1 POLICIES
8.1.1 Balancing Safe Yield and Overall Demand
When new water sources are obtained, the additional safe yield shall be allocated first to eliminate
any deficit between the adopted safe annual yield (Section 1.0) and the present demand as defined in
Policy 3.1.4, second to eliminate any deficit between adopted safe yield and General Plan build -out.
8.1.2 Supplying New Development
A. The City will determine the water available for allocation to new development by either, the
adopted safe annual yield of the City's water supplies minus present demand. as identified. in
Policy 3.1.4, or the projected demand at build -out as identified in Policy 3.1.3 minus present
demand as identified in Policy 3.1.4; whichever is less. based selely en the adopted per- eapita
Available allocations will be assigned to development in a way that supports balanced growth,
consistent with the General Plan. Allocations from a new water supply project shall be
considered available at the time project construction is initiated.
B. Any safe annual yield from new water supply projects beyond that needed to balance safe annual
yield and present demand will be allocated to development, subject to the requirements in Policy
8.1.3, "Reserve for Intensification and Infill."
C. A water allocation shall not be required for projects for which the developer makes changes in
facilities served by the City that will reduce long -term water usage equal to twice the water
allocation required for the project.
8.1.3 Reserve for Intensification and Infill Development
The City will annually update the water available for allocation based on the difference between the
adopted safe annual yield (policy 1. 1.2) and the present water demand (policy 3.1.4) as part of the
annual Water Resources Status Report. One -half of the water available for allocation (not to exceed
the total required for infill and intensification), as identified in the Water Resources Status Report,
will be reserved to serve intensification and infill development within existing city limits as of July
1994.
8.1.4 Accounting for Reclaimed Water
Reclaimed water has an estimated potential of 1,200 acre feet per year of water available for
appropriate non - potable uses. The amount to be added to the City's safe annual yield, and therefore
available for development, will only be the amount projected actually to be used or offset
(approximately 130 a.f. initially), increasing to 1,200 acre feet per year as additional offsetting uses
are brought on -line. The amount of reclaimed water used each year will be reported to Council as
part of the annual Water Resources Status Report and will be added to the safe annual yield
13
Exhibit A
C
City of SLO General Plan Water& Wastewater Management Element
identified in Section 1, Table 1 of this document to determine water available for new development.
8.15 Private Water Supplies
When developments are supplied by private groundwater wells, the yield of those wells will not be
counted toward the City's safe annual yield. Such yield, however, will result in the demand for City
water supplies being lower than it otherwise would be, which may necessitate adjustments of the per
capita water usage figure used to estimate overall demand.
BACKGROUND
The City has pursued numerous water supply projects over the years. (These projects are discussed
in Chapter 3 of the Urban Water Management Plan.) This part of the element addresses allocation of
these supplies once the yields from projects are realized. The City has identified these potential uses
for new supplies:
• Eliminating any deficit between adopted planning figures and safe annual yield;
• Providing for water requirements for future development within the urban reserve area
designated in the General Plan;
• Compensating for reduced yields due to reservoir siltation;
• Establishing a feliability FesenzeProviding additional water supplies, as determined by Council,
for drought, operational requirements for meeting peak demands, and other water supply
emergencies;
■ Providing water for habitat management.
Allocation of new supplies can balance the needs of all areas identified while not compounding the
potential water shortage problems for existing City water customers.
The adoption of 145 gallons/per person/per day as a water supply planning figure would indicate
water is available for development, eliminating the need for retrofitting. Because 145 gallons/per
person/per day assumes that the retrofit component of the water conservation program is complete,
new development will continue to retrofit until the entire city is essentially retrofitted as determined
by the City Council.
9.0 WATER ALLOCATION AND OFFSETS
9.1 POLICIES
9.1.1 Exemptions for Offsets
A. The City will not allow a project to reduce or eliminate the amount of the required allocation or
offset, to the extent that the project is supplied by a private well, with the following exceptions:
1. The City may reduce the amount of the required water allocation, to the extent that the
project is supplied by a private well serving non - potable water needs (such as irrigation)
which will not significantly affect the yield of City wells. Such a well may be operated by
14
Exhibit A
0
City of SLO General Plan Water & Wastewater Management Element
the owner of the property containing the well only for the owner's use. As an exemption, the
City may allow a well to supply landscape irrigation on more then one parcel if the irrigation
is:
a. for the common area of a condominium complex or other developments with similar
common areas as approved by the Utilities Director, and the well and irrigation
system are under the control of an owner's association; or
b. in a single commercial development, and the well and irrigation system are subject to
a recorded agreement among parcel owners, which is acceptable to the Utilities
Director and the City Attorney, and which establishes responsibilities for operation
and maintenance of the common areas served by the well.
2. When an allocation or potential offset is not available, a well maybe allowed to eliminate the
required offset for potable water needs only as an interim source until a new City water
source is available. Once a new source becomes available, the project will be required to
acquire an allocation from the City. Impact fees will be due at the time the development is
approved.
3. The City Council approves the well proposal as part of a specific land development project
approval, and the proposed well system meets all City standards; and
4. A qualified, independent, hydrological investigation demonstrates that the well(s) reliably
can provide sufficient quality and quantity of water for the proposed land development
project and will not impact the yields from City wells.
9.1.2 Basis for Allocations and Offsets
Required allocations and offsets will be based on long -term usage for each type of development.
("These use and offset factors will be determined and published by the City, and may be revised, as
warranted, by new information.)
BACKGROUND
In 1988, the City began to formally account for long -term water usage in new development. The
allocations have been based on histories of water usage for various kinds of development. At first,
the City decided to allocate some water for new land development projects even though city -wide
water usage exceeded safe yield. As the 1986 -1991 drought continued, and the projected completion
of proposed supplemental supply projects moved farther into the future, the City decided that there
should be no new development that would increase water usage. As a result, nearly all construction
since 1990 has been:
■ Replacement buildings, using the same or less water;
■ Additions or remodels which do not substantially affect water usage; and
15
Exhibit A
L' D
City of SLO General Plan Water & Wastewater Management Element
■ Projects that have retrofitted facilities served by the City, to save (offset) twice the amount of
water that would be allocated to the project. Installation of low -flow toilets, showerheads, and
faucets have accounted for most of the offset credit. Substantial credits were also earned by
installing water - recycling equipment in businesses.
Also, a few relatively small projects were able to do little or no retrofitting because they were
supplied with groundwater through private wells. Some projects have utilized more than one of
these strategies to proceed despite the lack of water allocations.
10.0 RECLAIMED WATER
10.1 POLICIES
10.1.1 Reclaimed Water Quality
The City will produce high quality reclaimed water, suitable for a wide range of nonpotable uses.
10.1.2 Uses of Reclaimed Water
The City will make available reclaimed water to substitute for existing potable water uses as allowed
by law and to supply new nonpotable uses.
When deemed appropriate by the Utilities Director, new development shall be equipped with dual
plumbing to maximize the use of reclaimed water for non - potable uses.
BACKGROUND
Reclaimed water is highly treated wastewater (sewage) which can be used for most nonpotable
purposes. The City's Water Reclamation Facility (formerly known as the Wastewater Treatment
Plant) has been upgraded to the point the effluent can be used directly for landscape and agricultural
irrigation and other uses such as industrial processes and toilet flushing in certain types of buildings.
Most treated effluent, in the past, has been discharged to San Luis Obispo Creek. A small amount of
effluent has been used at the treatment plant site for landscape irrigation. Reclaimed water will be
used for additional landscape irrigation at the Water Reclamation Facility and on City-owned land in
the vicinity, and for ponds to benefit wildlife.
Use of reclaimed water beyond the treatment plant area will require a distribution system separate
from other water lines. Reclaimed water can be used to supply nonpotable uses in new development
and to offset potable uses in existing development. These potential uses require a deliberate method
to account for reclaimed water use, consistent with policies concerning total water requirements-and
other water sources.
16
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
Long -term funding for the necessary reclaimed water distribution system is expected to come from
charges for the use of reclaimed water. Initial expenses may be funded from bonds, low- interest State
loans, and developer contributions.
11.0 WATER SERVICE WITHIN THE CITY
11.1 POLICY
11.1.1 Water Service- within the City
A. The City will be the only purveyor of water within the City.
B. Appropriate use of privately owned wells may be allowed with the approval of the Utilities
Director, consistent with policies 8.1.5 and 9.1.1.
BACKGROUND
Historically, the City has been the sole water purveyor within the City limits. This allowed the City
to maintain uniformity of water service and distribution standards, and to be consistent in developing
and implementing water policy. In continuing to be the sole water purveyor, the City will maintain
control over water quality, distribution and customer service, as well as ensure consistency with the
City's General Plan policies and goals.
17
Exhibit A
c
City of SLO General Plan Water & Wastewater Management Element
WASTEWATER SECTION
GOAL
San Luis Obispo's wastewater goal is to provide efficient and environmentally acceptable wastewater
disposal service for the community.
12.0 SERVICE -AREA AND POPULATION
12.1 POLICIES
12.1.1 Service Area
The current wastewater service area is the incorporated area of the City. The City shall provide
wastewater service adequate for existing uses and new development pursuant to the Land Use
Element for all areas within the city limits.
12.1.2 Areas Within the Urban Reserve Line
The urban reserve line (the outer limit to urban development) includes areas which the City may
annex in the future. Wastewater service adequate for potential uses allowed by the Land Use
Element (including hillside planning provisions) shall be provided for all areas within the urban
reserve line.
12.1.3 Service Outside the City Limits
To receive City wastewater service, areas must be annexed to the city. The City will not provide
wastewater service for areas outside the city limit, except for:
A. Customers which have prior agreements.
B. Uses which are consistent with the General Plan and which are located on areas of less than
one acre, which are surrounded on at least three sides by areas that are already served.
12.1.4 Areas Outside the Urban Reserve Line
The City will not provide wastewater service to areas outside the urban reserve line.
12.1.5 Special Districts
Special districts should not provide wastewater service within the City's planning area to uses
inconsistent with the City's General Plan.
W-1
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
12.1.6 Service Capacity
The City's wastewater collection and treatment systems must be able to support population and
related service demands consistent with General Plan objectives. These basic objectives are stated in
the Land Use Element (growth management) and in the Housing Element.
12.1.7 Annexation Criteria
The City will not annex an area unless it can meet the wastewater treatment needs of the area to be
annexed, in addition to the wastewater treatment requirements for all development, consistent with
the Land Use Element, within the city including the annexed area. The only exceptions to this policy
are:
A. Areas which have prior agreements for wastewater service.
B. Minor infill parcels within areas which have prior agreements for wastewater service, as
provided in policy 12.1.3.
12.2 PROGRAMS
12.2.1 Updates
The City will update this element's service area description and population projections as needed and
in concert with any amendments to the Land Use Element.
Time frame: continuing
Responsible parties: Community Development Department; Planning Commission, City Council.
Funding: City general fund.
12.2.2 Projections of Requirements
The City will refine this element's projections of wastewater treatment requirements on the basis of
wastewater flows from specific land use categories and the likely development of those categories as
provided in the Land Use Element.
Time frame: Following adoption of the Land Use Element update.
Responsible parties: Community Development Department; Utilities Department; Planning
Commission; City Council.
Funding: City general fund-
12.2.3 Expanding Capacity
The City will expand the capacity of the wastewater treatment plant to provide adequate treatment
for projected wastewater flows.
Time frame: Late 1980's to late 1990's.
Responsible parties: Utilities Department; City Council.
Funding: Development and connection charges, wastewater fees, and grants.
19
Exhibit A
City of SIA General Plan Water & Wastewater Management Element
13.0 WASTEWATER COLLECTION, TREATMENT, AND DISPOSAL
13.1 POLICIES
13.1.1 Stormwater Infiltration
The City will minimize stormwater infiltration into the sewer system.
13.1.2 System Protection
The City will minimize damage to the wastewater collection and treatment systems by preventing
discharge of materials that are toxic or which would obstruct flows.
13.13 Managing Treatment Demand
The City will manage wastewater treatment demand to assure that it can provide a high level of
wastewater service.
13.1.4 Beneficial Use
The City will pursue treatment and disposal methods which, to the maximum extent feasible, provide
for further beneficial use of wastewater and allow beneficial uses of land or water receiving the
effluent.
13.15 City as Exclusive Provider
The City will be the only provider of public wastewater treatment within the City (but on -site
pretreatment of wastewater to meet City Standards may be required).
13.1.6 Energy Efficiency
Wastewater operations will minimize energy use and will incorporate cost - effective energy recovery
or production facilities.
13.2 PROGRAMS
13.2.1 Reducing Infiltration
The City will continue to investigate and cant' out cost - effective methods for reducing stormwater
flows into the wastewater system.
Time frame: Continuing
Responsible agencies: Utilities Department; City Council
Funding: Wastewater revenues
20
Exhibit A
�!
City of SLO General Plan Water & Wastewater Management Element
13.2.2 Discharge Standards
The City will update and enforce its standards for the quality of wastewater discharged to the system.
Time frame: Continuing
Responsible agencies: Utilities Department; City Council
Funding: Wastewater revenues
13.2.3 Project Evaluation
The City will continue to evaluate the potential for the wastewater flows of a proposed project to
exceed the capacity of collection and treatment systems.
Time frame: Continuing
Responsible agencies: Utilities Department; Community Development Department; City
Council
Funding: General fund
13.2.4 State and Federal Water Quality Standards
The City will change its treatment and disposal practices in an attempt to meet federal and state
water - quality standards. The first step will be adoption of the Wastewater Management Plan and
completion of pre- design technical reports that will describe a specific strategy for treatment and
disposal. Any additional required environmental review would be integrated with the pre- design
work. Then, plans and specifications, and a budget, for the construction project would be prepared.
The timing of these steps will be worked out in collaboration with the. Regional Water Quality
Control Board.
Time frame: Construction complete in the early 1990's
Responsible agencies: Utilities Department; City Council
Funding: Wastewater revenues; state or federal grants
14.0 WASTEWATER REVENUES AND FINANCING
14.1 POLICY
14.1.1 Enterprise Activity
The City's wastewater system will be operated as an enterprise activity, with costs to be borne by
wastewater fees and charges. Costs of operating, maintaining, and replacing the wastewater system
will be borne by all customers. Some portion of the costs of making major decisions about the
wastewater systems —such as evaluating changes to citywide collection and treatment — may be borne
by the whole community. Costs of expanding treatment capacity and extending the collection system
to serve new development shall be borne by those making new connections to the system, in
proportion to expected wastewater flows. The City will seek any state or federal grants which may
be available to fund sewer system improvements. Programs to fund wastewater projects should be
consistent with the growth management policies of the General Plan.
21
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
14.2 PROGRAM
14.2.1 Revising Charges
The City will periodically revise its schedule of charges for wastewater service. The city will prepare
a development fee schedule to fund expansion of collection and treatment facilities.
Time frame: Periodic rate evaluation; development fees to be adopted by July 1988 and updated
as required.
Responsible paAies: City staff; City Council.
WASTEWATER BACKGROUND
Current Wastewater Flows and Treatment
The City is responsible for collecting, treating, and disposing of wastewater from about 19,000
residential, commercial, industrial, and public customers every day, in a way that avoids
environmental and public health problems. In addition to homes and businesses within the city
limits, the City provides wastewater services for Cal Poly and the County airport.
The City's existing wastewater collection system partly determines the character of wastewater flows.
About 150 miles of sewer pipes, ranging from six to 30 inches in diameter, collect wastewater
flows. The oldest pipes date from the 1890's, when pipe materials and trenches were less able to
withstand the effects of corrosion and soil settlement. Eight pumping stations move the wastewater
from areas where the slope of sewer pipes is not sufficient to allow gravity flow. Sewer lines cross
creeks at 95 locations in the City; at some locations, siphons (U- shaped sections of pipe) allow the
flows to continue. In some places, newer pipes have been installed parallel to older pipes to handle
increased flows.
Despite the City's efforts to repair and replace older and deteriorated sewer pipes, some cracked
joints between pipe sections, some manhole covers, and improperly connected storm - water drains
allow water from rainfall and saturated ground to enter the sewage collection system. This storm
water infiltration significantly increases the amount of wastewater that must be treated during the wet
season. Undersized and damaged lines, siphons, and parallel pipes are often the source of wastewater
collection problems.
Collected flows are treated at the City's plant on Prado Road near Highway 101. The plant removes
floating and large, gritty material, reduces the amount of nutrients and bacteria, separates sludge
from the waste stream, and discharges the effluent into San Luis Obispo Creek near Los Osos Valley
Road. Sludge is separated from the wastewater, dried in open ponds at the treatment plant, and
hauled away for use on landscaping or crops. While the treatment plant uses tanks, pumps, and other
mechanical equipment, most of the wastewater treatment is actually done by living microorganisms.
The man-made features are largely to provide a suitable place for them to grow.
22
Exhibit X:.
7
City of SLO General Plan Water & Wastewater Management Element
Wastewater flows are measured in millions of gallons per day -- abbreviated "mgd." (One million
gallons would fill a tank 60 feet in diameter and 50 feet high.) In 1986, the average flow into the
treatment plant during dry weather was 4.4 mgd. During wet weather, the peak flow was 22.4 mgd.
Standards for quality of the treated effluent follow from federal and state water - quality laws. The
specific requirements for San Luis Obispo were most recently set by the state's Regional Water
Quality Control Board in April 1986. The standards are to protect present and potential beneficial
uses of the water which receives the effluent, including recreation, agricultural. supply, and fish and
wildlife habitat. The standards include:
• For the creek -maximum allowed changes in acidity /alkalinity, temperature, and oxygen;
• For the effluent - maximum allowed quantities of solid particles and dissolved solids,
nutrients which deprive the water of oxygen through chemical and biological action, oil and
grease, coliform bacteria, and chlorine left from the last treatment step.
Effluent quality has violated the standards, so the Regional Water Quality Control Board has ordered
the City to improve the effectiveness of its treatment. The primary problem has been the amount of
nitrogen in the form of ammonia. Other nutrients, suspended solids, oil and grease, and coliform
bacteria have also exceeded the standards.
Projected Wastewater Flows
If the City grows to about 53,000 population in the year 2015, as outlined in the Land Use Element,
the average dry- weather volume of wastewater is expected to increase by about 32 percent, from 4.4
mgd to 5.8 mgd. Other measures of required treatment capacity, such as flow in the peak month and
the amount of nutrients and solids, are expected to increase in about the same proportion.
Consulting engineers have concluded that the existing wastewater treatment plant site is big enough
for a plant to handle the projected flows, but the treatment plant will have to be changed to treat such
flows effectively. The City plans a two -phased expansion of treatment capacity. The first phase
would also improve the effectiveness of treatment. Both phases involve changing and enlarging
certain facilities at the treatment plant
Alternative Treatment and Disposal Methods
Many different methods of disposing of treated wastewater (effluent) have been considered. Each
method has its own advantages and disadvantages. In evaluating treatment and disposal methods, the
City will consider initial and continuing costs, environmental impacts, reliability, flexibility, and
potential for increasing beneficial uses of treated wastewater. Preliminary evaluations have indicated
that some of the options listed below are not feasible or cost - effective. The feasibility and desirability
of others will not been known until additional evaluations are completed, and even then changing
conditions may warrant reconsideration or further study.
The City does not want to preclude treatment and disposal options which may turn out to be feasible.
However, the City must select an overall strategy for treatment and disposal and begin to cant' it out,
in order to meet established water - quality standards. Once a strategy is chosen and money is
23
Exhibit A
City of SLO General Plan Water & Wastewater Management Element
committed to certain physical projects, those funds would not be available to spend on significantly
different strategies.
Several alternatives to conventional stream disposal, which could be used in various combinations,
are briefly described below. With the exception of an ocean outfall, each alternative involves some
beneficial use — reclamation -- of the treated wastewater, as does direct stream disposal (which helps
maintain stream habitat and recharges downstream wells). Reclaiming all the effluent for uses that
would otherwise need fresh City water, which is not likely in the time frame of this element, would
displace the need for about 5,000 acre-feet of water in 1987, and about 6,600 acre -feet in 2015.
Irrigation
Effluent could be used to irrigate recreational land (such as a golf course) or agricultural land.
Effluent used for pasture irrigation would probably not have to meet standards as high as those
for creek disposal. However, to dispose of all projected effluent quantities during all seasons, the
City would have to own or permanently control the use of about 2,000 acres of land. Even with
availability of such a large area for irrigation, a substantial holding pond would be required for
winter storage, when the ground is saturated. The main obstacles to this approach are obtaining
the required disposal area, piping the effluent to it, and assuring no long -term harm to soil
characteristics or groundwater supplies. Effluent used to irrigate landscaping or recreational land
could replace water from other sources, or it could enable expansion of landscaped or
recreational areas without drawing on limited supplies of fresh water.
Stream Improvement
The creek's ability to provide good wildlife habitat can be improved in ways other than removing
certain contaminants from the effluent. Effluent, possibly with more nutrients or discoloring
substances than now allowed, could be discharged at several points within an enlarged
streamside forest. Additional streamside trees and plants (a riparian corridor) would help remove
nutrients. They would also shade the water, and could therefore help keep it cooler. Along with
using such natural treatment capacity, the City could restore some of the habitat downstream
from the treatment plant, which has been harmed by vegetation removal and intensive livestock
use. The City's improving the habitat might allow relaxation of some discharge standards, since
creation of a riparian corridor would enhance a beneficial use which the Regional Water Quality
Control Board is trying to protect.
Groundwater Recharge
If suitable areas could be found and used by the City, effluent could be deliberately spread to
percolate into the ground to recharge aquifers. While stream disposal does this for some
downstream areas, disposal at other locations might allow more of the water to be retained where
it could be withdrawn efficiently for use by the City.
Laguna Lake or Marsh
Effluent could be used to maintain a fairly constant level of Laguna Lake year- round. Much of
the effluent would still make its way to San Luis Obispo Creek. If the effluent entered the lake
directly, the required level of treatment would exceed that for direct stream disposal, since the
lake is used for water - contact sports. Discharging the effluent into the marsh at the northerly end
of the lake, or as pasture or landscape irrigation, would allow some natural filtering and might
require a lower level of treatment than direct stream disposal.
24
EmDlt A..
City of SLO General Plan _ Water & Wastewater Management Element
Industrial Reuse
Some industries use large quantities of water that need not be of drinking quality. San Luis
Obispo does not have significant manufacturing or processing industry, though it does have some
businesses, such as laundries, which might be able to use properly treated effluent. Such effluent
as a source of water also might enable industries that could not otherwise locate in San Luis
Obispo to do so.
Aquaculture
Sewage is basically heavily fertilized water. If proper growth conditions are provided and
harmful substances-are controlled, the water -borne nutrients can be converted to useful plants
and animals through aquaculture. Water hyacinth (used to produce methane, soil conditioner, or
livestock feed) and several varieties of fish have been produced in municipal wastewater
treatment plants. Difficulties with this approach include finding and maintaining markets for the
products and continuously providing acceptable levels of treatment with widely varying
wastewater flows and weather conditions.
Domestic Reuse
With substantially higher levels of treatment than now used and a suitable distribution system,
wastewater could provide for the full range of household uses. However, meeting state and
federal standards for quality of drinking water would be very difficult. The costs of adequate
treatment and distribution, even for household landscape irrigation, far exceed other alternatives
and are expected to be prohibitive for the foreseeable future.
Ocean Outfall
Coastal communities dispose of their effluent in the ocean. San Luis Obispo could pipe its
treated effluent to San Luis Bay. However, the costs of building and maintaining a pipeline to the
ocean appear greater than the savings that might be achieved through meeting the somewhat
lower effluent standards for ocean disposal. Coastal Commission approval would be required for
an ocean outfall.
Wastewater Costs and Revenues
The City budgets its wastewater activities separately from other City services and has a long - standing
policy that wastewater revenues should fully fund wastewater services. Those making new
connections to the sewer system pay for some of the cost of developing the existing system.
Residential customers and most small businesses are billed at a.uniform monthly rate, while some
larger businesses pay according to the amount of water they use. In 1986 -87, the City sewer system
budget was $1.1 million.
To fund anticipated treatment -plant and collection- system changes through the 1990's, the City
probably will need to substantially increase sewer rates, even with federal grant funding. Also,
federal rules may require the City to revise its rate structure, so users are charged according to the
average and peak quantities and concentration of contaminants of the wastewater they produce.
M
0
w
U-1 aerK
city of san WIS OBISPO
GENERAL PLAN
WATER & WASTEWATER
MANAGEMENT ELEMENT
June 2004
$2.50 16-04
city of san lugs oBIspo
community bEvelopmEnt bepaRtmEnt
our mission statement
our mission is to senve all persons in a positive anb
courteous manner anb help ensure that san Luis
OBISpo continues to Be a healthy, safe, attnactive, anb
enjoyaBLe place to Live, work, on visa. we help plan the
city's foam anb chanacten, support community values,
pnesenve the environment, promote wise use of
nesounces, anb protect puBLic health anb safety.
ouu service philosophy
the city of san WIS OBISpo community bevelopment
bepantment staff pnovibes high quaLity senvice when
you necb It. we wilt:
✓ Listen to unbenstanb your neebs;
✓ gIve clean, accurate anb prompt answers to your
questions;
✓ explain how you can achieve your coals unben
the city's nules;
✓ help Resolve pnoBLems in an open, oBjective
manner;
✓ maintain high ethical stanbanbs; anb
✓ wonk to impnove our senvice.
The City's General Plan is made up of sections called "elements." Each element focuses on
certain topics as required or allowed by State law. According to State law, each element has
equal weight in defining City policies. In September 2002, the following elements comprised the
City's General Plan.
Idle
Adoption or Li3st Ma or ReVisiori Date
Land Use
1994
Housing
2004
Circulation
1994
Open Space*
1994
Conservation*
1973
Parks & Recreation
2001
Noise
1996
Safety
2000
Energy Conservation*
1981
Water & Wastewater Management
1996
*Update in progress.
City Council
Dave Romero, Mayor
John Ewan
Allen Settle
Christine Mulholland
Ken Schwartz
Planning Commission
James Caruso, Chair
Michael Boswell
Jim Aiken
Andrea Miller
Carlyn Christianson
Alice Loh
Orval Osborne
Administration
Ken Hampian, City Administrative Officer
Wendy George, Assistant City Administrative Officer
Community Development Department
John Mandeville, Director
Michael Draze, Deputy Director for Long -Range Planning
Michael Codron, Associate Planner
Utilities Department
John Moss, Director
Gary Henderson, Water Division Manager
David Hix, Wastewater Division Manager
Dan Gilmore, Utilities Engineer
Sue Baasch, Utilities Analyst
Ron Munds, Utilities Conservation Coordinator
City of San Luis Obispo
General Plan
Water & Wastewater Management Element
This element was first adopted February 24, 1987, by City Council Resolution No. 6180A. The
following amendments have been adopted:
Topic Date Council Resolution Number
Wastewater section added October 26, 1987 6351
Revised water section November 15, 1994 8370
Water offset potential for annexations,
accounting for reclaimed water, and use
of wells July 2, 1996 8560
Clarifying water allocation to develop-
ment, required offsets, and use of wells December 13, 1999 9003
Accounting for siltation and correcting May 16, 2000 9044
safe yield information
Reliability reserve, offsets, siltation, and September 3, 2002 9363
reclaimed water
Various policies relating to supplemental June 29, 2004 9584
water supplies (Nacimiento)
City of SLO General Plan Water & Wastewater Management Element
CONTENTS
INTRODUCTION........................................................................................................................ 1
WATER SECTION
I. Safe Annual Yield............................................................................................................... 2
2. Water Conservation............................................................................................................ 5
3. Water Demand Projections................................................................................................ 6
4. [reserved section number]
5. Siltation at Salinas and Whale Rock Reservoirs.................................................................. 9
6. Supplemental Water Requirements................................................................................... 10
7. Multi -source Water Supply.............................................................................................. 12
8. Allocation of New Water Supplies................................................................................... 12
9. Water Allocation and Offsets............................................................................................14
10. Reclaimed Water............................................................................................................ 15
11. Water Service within the City.......................................................................................... 16
WASTEWATER SECTION
12. Service Area and Population............................................................................................ 17
13. Wastewater Collection, Treatment, and Disposal.............................................................. 19
14. Wastewater Revenues and Financing............................................................................... 20
TABLES
NUMBER TITLE Page
1 Safe Annual Yield................................................................................................ 3
2 Water Use 1980 - 1999........................................................................................... 7
3 Per Capita Water Use............................................................................................. 8
4 Calculation of Present (2002) Water Demand ....................................................... 8
5 Salinas Reservoir Capacity Studies..................................................................... 10
6 Required Safe Annual Yield for General Plan Build -out ...................................... 11
City of SLO General Plan Water & Wastewater Management Element
INTRODUCTION
The City's General Plan guides the use and protection of various resources to meet community
purposes. It reflects consensus and compromise among a wide diversity of citizens' preferences,
within a framework set by State law. The General Plan contains elements that address various
topics.
The City decided to adopt an element addressing water resources and wastewater treatment because
of the vital role of these resources and the far-reaching impacts of water policies on community
growth and character. This element translates the Land Use Element's capacity for development into
potential demand for water supply and wastewater treatment. This element outlines how the City
plans to provide adequate water and wastewater services for its citizens, consistent with the goals
and policies of other General Plan elements.
Before adopting or revising any General Plan element, the Planning Commission and the City
Council must hold public hearings. The City publishes notices in the local newspaper to let citizens
know about the hearings at least ten days before they are held. Also, the City prepares environmental
documents to help citizens understand the expected consequences of its planning policies before the
hearings are held.
Anyone may suggest or apply for amendments to General Plan elements. The City will probably
update this element about every five years, or more frequently if necessary.
City of SLO General Plan Water & Wastewater Management Element
WATER SECTION
1.0 SAFE ANNUAL YIELD
1.1 POLICIES
1.1.1 Basis for Planning
The City will plan for future development and for water supplies based on the amount of water
which can be supplied each year, under critical drought conditions. This amount, called "safe annual
yield," will be formally adopted by the Council. The safe annual yield determination will be revised
as significant new information becomes available, and as water sources are gained or lost. The
determination will consider a staff analysis, which will recommend an amount based on coordinated
use of all water sources. Each change to safe annual yield will be reflected in an amendment of this
Plan.
1.1.2 Safe Yield Amount
The City's safe annual yield, from the coordinated operation of Salinas and Whale Rock reservoirs
and 500 acre feet of groundwater, is shown in Table 1. The safe annual yield includes reductions due
to siltation at the reservoirs, discussed in more detail in Section 5.0.
1.1.3 Groundwater
A. The amount of groundwater which the City will rely upon towards safe annual yield is
identified in policy 1.1.2. The City will maximize the use of groundwater in conjunction
with other available water supplies to maximize the yield and long-term reliability of all
water resources and to minimize overall costs for meeting urban water demands. The City
shall monitor water levels at the well sites to determine whether reduction or cessation of
pumping is appropriate when water levels approach historic low levels.
B. The City will not compete with local agricultural use of groundwater outside the urban
reserve line or damage wildlife habitat through reduced natural stream flows in obtaining
long-term sources of water supply.
BACKGROUND
Safe annual yield is the amount of water that can reliably be produced by the City's water supply to
meet the water demand. It is estimated by simulating the operation of the City's water supply sources
over an historical period to determine the maximum level of demand that could be met during the
most severe drought for which records are available.
The safe annual yield of an individual source of water supply is defined as the quantity of water
which can be withdrawn every year, under critical drought conditions. Safe annual yield analyses of
water supply sources are based on rainfall, evaporation and stream flow experienced during an
2
City of SLO General Plan Water & Wastewater Management Element
historical period. The City of San Luis Obispo uses a period beginning in 1943, which covers
drought periods in 1946-51, 1959-61, 1976-77, and 1986-91. The historical period used in the latest
computer analysis to determine safe annual yield extends from 1943 through 1991 and includes the
most recent drought. Although future conditions are unlikely to occur in the precise sequence and
magnitudes as have occurred historically, this technique provides a reliable estimate of the future
water supply capability of the existing sources, since the long term historical record is considered a
good indicator of future conditions.
The safe annual yield gradually declines as silt accumulates in the reservoirs, thereby reducing
storage capacity (discussed in more detail on page 10).
Prior to 1991, the "controlling drought period" for determining safe annual yield was 1946 to 1951.
The critical period for determining safe annual yield from the two reservoirs is now the period from
1986 to 1991. The safe annual yield is reflected in the table below and includes estimated losses
associated with siltation.
TABLE 1
SAFE ANNUAL YIELD
Year
Salinas_&.Whale
.'RockReservoirs-
Groundwater'.
Total = .
...
_,
2000
7,040 acre feet
500 acre feet
7,540 acre feet
2001
7,030 acre feet
500 acre feet
7,530 acre feet
2002
7,020_ acre feet
500 acre feet
7,520 acre feet
2003
7,010 acre feet
500 acre feet
7,510 acre feet
2004
7,000 acre feet
500 acre feet
7,500 acre feet
2005
6,990 acre feet
500 acre feet
7,490 acre feet
2006
6,980 acre feet
500 acre feet
7,480 acre feet
2007
6,970 acre feet
500 acre feet
7,470 acre feet
2008
6,960 acre feet
SOQ acre feet
7,460 acre feet
2009
6,950 acre feet
500 acre feet
7,450 acre feet
Previous Safe Annual Yield Studies
Previous studies of the critical historical drought periods at Salinas and Whale Rock reservoirs have
indicated the following safe annual yields were available to the City:
Water Supply
Salinas Reservoir
Whale Rock Reservoir*
Coordinated Operation
Groundwater
TOTAL
Safe Annual Yield
4,800 acre-feet
2,060 acre-feet
500 acre-feet
500 acre-feet
7,860 acre-feet
*City's share of Whale Rock Reservoir safe annual yield.
K
Reference
Corps of Engineers, 1977
Dept Water Resources, 1974
CH2M-Hill, 1985
Water Operational Plan, 1993
City of SLO General Plan Water & Wastewater Management Element
Past safe annual yield analyses for the two reservoirs assumed independent operation and historical
data to the date of each report. The critical drought period for the previous studies was 1946-51.
The studies also assumed a minimum pool at Salinas and Whale Rock of 400 and 500 acre-feet
respectively. "Coordinated operation" is a concerted effort to operate the two reservoirs together for
maximum yield. Since Salinas Reservoir spills more often than Whale Rock Reservoir, due to its
larger drainage area and more favorable runoff characteristics, and has higher evaporation rates, the
combined yield from the two reservoirs can be increased by first using Salinas to meet the City's
demand and then using Whale Rock as a backup source during periods when Salinas is below
minimum pool or unable to meet all of the demand. The 500 acre-feet increase in safe annual yield
was a preliminary estimate of the additional yield attributed to coordinated operations of the
reservoirs identified in the 1985 report prepared by CH2M-Hill.
In 1988, the City contracted with the engineering firm of Leedshill-Herkenhoff, Inc., to prepare a
detailed analysis of the City's water supplies and safe annual yield, based on coordinated operation of
the reservoirs. The report "Coordinated Operations Study for Salinas and Whale Rock Reservoirs"
was completed in 1989. The study estimated total safe annual yield for the City from the two
reservoirs to be 9,080 acre-feet per year. Since the study period was only to 1988 and the City was in
a drought period of unknown length, this amount was never adopted by Council. It should be
emphasized that this estimate assumed that the "controlling drought period" was 1946 to 1951 and
that Whale Rock Reservoir is used only when Salinas is below minimum pool or can not meet the
monthly City demand, and does not consider limitations on the use of Salinas water due to water
quality constraints. Following the end of the 1986-1991 drought, staff updated the computer program
created by Leedshill-Herkenhoff to estimate the impact of the drought on safe annual yield of the
reservoirs. The analysis determined that the recent drought was the critical drought of record for the
two reservoirs and resulted in a reduction in the safe annual yield.
Groundwater Resources
The groundwater basin that underlies the City of San Luis Obispo is relatively small. Therefore,
extractions in excess of 500 acre-feet per year during extended drought periods cannot be relied
upon. Because the basin is small, it tends to fully recharge following significant rainfall periods.
Following periods of above average rainfall, the groundwater basin may be capable of sustaining
increased extraction rates to meet City water demands. Since both Salinas Reservoir and the
groundwater basin fill up and "spill' following significant rain periods, there is a benefit in drawing
from these sources first and leaving Whale Rock Reservoir as a backup supply. The conjunctive use
of the groundwater basin and surface water supplies in this manner will provide an effective
management strategy that increases the reliability of all the resources to meet current and future
water demands.
Another benefit of maximizing groundwater use is that it typically requires minimal treatment that
reduces costs compared to surface water supplies. Even with treatment for nitrates and PCE, the
projected costs associated with that treatment show groundwater to be comparable to other
alternative future water supply projects.
Past City policy has been not to compete with agriculture for use of groundwater resources.
Recognizing the importance of the production of food and fiber as well as open space provided by
agricultural land outside the urban reserve line, the City will continue to endorse this policy.
4
City of SLO General Plan Water & Wastewater Management Element
2.0 WATER CONSERVATION
2.1 POLICIES
2.1.1 Long-term Water Efficiency
The City will implement water -efficiency programs which will maintain long-term, per -capita usage
at or below the per capita use rate as identified in Policy 3.1.2.
2.1.2 Short-term Water Shortages
Short-term mandatory measures, in addition to the long-term programs, will be implemented when
the City's water supplies are projected to last three years or less based on projected water
consumption, coordinated use of all city water supply sources, and considering the drought pattern
on which safe yield is based (or response to other situations which may interrupt supply).
BACKGROUND
Water conservation was referenced as a part of the City's water management policy in 1973. In 1985,
the City adopted the Annual Water Operational Plan policy that established water conservation as a
means of extending water supplies during projected water shortages. Since 1985, many
technological and philosophical changes have occurred which are proving water conservation to be
both a short term corrective measure for immediate water supply shortages and a long term solution
to water supply reliability.
A comprehensive evaluation of the potential water savings from current water conservation
technologies and programs is included as Appendix V to this Plan. Based on the reliability of the
water conservation measures which were evaluated, and the cost effectiveness of the proposed
programs, a long term reduction in water demand of approximately twenty percent from the average
per capita use recorded in 1986-87 is used for planning for future water conservation programs as
well as future water supply needs.
Because of the experience during the drought of 1986 to 1991, the City has developed a short term
plan to deal with immediate water shortages and has recognized the importance of water efficiency
by supporting longterm programs. The City will reevaluate and update its water conservation efforts
in response to changing water demand; supplies, technology and economic conditions.
5
City of SLO General Plan Water & Wastewater Management Element
3.0 WATER DEMAND PROJECTIONS
3.1 POLICIES
3.1.1 Basis of Projections
The City will project water requirements, considering lonb term conditions and the full range of
water uses in the City.
3.1.2 Water Use Rate
The City shall use 145 gallons per person per day (this equates to approximately 0. 162 acre-foot per
person per year) and the number of City residents to plan total projected future water demand. This
quantity will be revised if warranted by long-term water use trends, including differences in the
relationship between residential and nonresidential usage. (Throughout this Plan, 145 gallons per
person per day is used in computations of future water demand.)
3.1.3 Overall Projected Demand
Applying 145 gallons per person per day to a projected City resident population of about 56,000 at
General Plan build -out results in a projected water demand of 9,096 acre-feet per year (excluding
demand from the Cal Poly campus, which has separate entitlements).
3.1.4 Present Water Demand
Present water demand shall be calculated by multiplying the water use identified in Policy 3.1.2 by
the current city population (as determined by the California Department of Finance, Population
Research Unit).
3.15 Peak Daily Water Demand
The City shall strive to develop and maintain water supply sources and facilities appropriate to
ensure sufficient supply and system capacity to provide the peak daily water demand of the City.
BACKGROUND
The City must know how much water will be needed to serve residents, businesses, and other users
to accommodate the General Plan. This quantity can be projected using different methods. All
methods involve assumptions about both future usage rates and the numbers and types of users
expected in the future. The quantity expressed in the policy above corresponds closely with both (1)
total city-wide usage compared with total resident population and (2) projections of water demand
based on usage by various land use categories. There always will be some uncertainty in estimating
development capacity (such as the number of dwellings or residents) as well as the usage per
customer type (such as acre-feet per dwelling or per resident.) The estimating method must use
reasonable assumptions, based on experience, to assure an adequate level of water supply while not
overstating demands.
Since the early 1970's, usage estimates have ranged from 0.17 to 0.22 acre-foot per resident per year
(about 155 to about 195 gallons per person per day). The estimates have varied so widely due to
is
City of SLO General Plan Water & Wastewater Management Element
actual differences in consumption over time and to confusion about accounting for Cal Poly usage.
(The City treats and delivers much of the water used by Cal Poly, even though Cal Poly has separate
entitlements.) Table 2 shows recent water usage compared with City resident population. Table 3
compares the "per capita" and "land use" methods of estimating water needs.
TABLE 2
WATER USE 1980-1999
Year
Water from Treat-
ment Plant and Wells
acre-feet (1)
Total City Water
Demand
acre-feet (2)
Population
(3)
Total Gallons
per Person per
Day
City Gallons
per Person
per Day
1980
6,745
6,145
34,252
176
160
1981
6,941
6,341
34,759
178.
163
1982
6,584
5,984
35,239
167
152
1983
6,800
6,200
35,660
169
155
1984
7,862
7,262
36,407
182
178
1985
8,025
7,425
37,378
193
177
1986
8,367
7,767
38,205
196
181
1987
8,399
7,799
38,282
196
182
1988
8,411
7,811
39,858
188
175
1989
6,004
5A4
41 027
129
118
1990
41796
4,196
41958
102
89
1991
45640
4,040
42178
98
86
1992
5,316
4,716
42,922
110
98
1993
5,572
4,972
43,415
115
102
1994
5,775
5,200
43,919
117
106
1995
6,075
5,574
41,295
131
120
1996
6;379
5,742
41,404
138
125
1997
6,868
6,220
41,807
147
133
1998
6,399
5,852
42,201
135
124
1999
6,736
6,172
42,446
142
129
Bold, italicized years (1989 - 1991) indicate mandatory conservation period.
(1) Data from City Water Treatment Plant production reports; includes Cal Poly potable water.
(2) Cal Poly water use assumed constant for years before 1994, at 600 acre-feet..
(3) January 1 population estimates from the California Department of Finance, Population Research Unit, as
revised through 1999.
City of SLO General Plan Water & Wastewater Management Element
TABLE 3
PER CAPITA WATER USE
Method 1: Water treatment plant production and
Method 2: Metered use by development type
Population
and Land Use Element
Per capita water use - based on historic demand,
Per capita water use - based on historic
population, and conservation
demand, land use, and conservation
Annual demand 1987 year highest use
8,397 acre-feet
General Plan build -out (1992 draft)
Land use types (with 20% reduction from pre -1987
1 acre-foot
Less Cal Poly Subtract 600 acre-feet
7,797 acre-feet
usage rates)
from total, based on average demand
325,851 gallons
Single family residential 3,630 acre-feet
7,216 acre feet
Multifamily residential 2,633
Retail commercial 422
Office 393
Per capita use Convert to gallons and
182 ga0ons/day
Services & manufacturing 438
divided by 365. Divide by Dept. of Finance
Motelfhotel 608
population estimate (38,282)
Hospitals, schools, parks 1,432
Total 9,566 acre-feet
Less 20% long-term conservation
145 gauonsiday
Per capita use Convert to gallons
152 gallons/day
and divide by 365. Divide by estimated
56,000 buildout population (excludes
Cal Poly residents).
Based on the analysis of these two approaches and the inclusion of long term water conservation
programs, 145 gallons per day per person is used throughout this element for long term water supply
planning purposes.
TABLE 4
CALCULATION OF PRESENT (2002) WATER DEMAND
Gallons per
City
Gallons per
Days in
person per day
Population
Acre Foot
a Year
Current Demand
1 acre-foot
145
44,426
325,851 gallons
365
7,216 acre feet
4.0 [Contents of Section 4.0 deleted by September 2002 amendment. Numbering of following
sections retained to avoid confusion in references among documents.]
0
City of SLO General Plan Water & Wastewater Management Element
5.0 SILTATION AT SALINAS AND WHALE ROCK RESERVOIRS
5.1 POLICY
5.1.1 Accounting for Siltation
The City shall account for siltation in the adoption of the safe annual yield as identified in Policy
1.1.2. The estimated annual reduction in safe annual yield from Salinas and Whale Rock Reservoirs
is 10 acre-feet per year. As Council considers and develops new water supply opportunities, Council
should consider planning for additional water to address siltation losses over a longer term.
BACKGROUND
Siltation at reservoirs is a natural occurrence that can substantially reduce the storage capacity over
long periods. The reduction of available storage will reduce the safe annual yield of the reservoirs.
Siltation at reservoirs varies depending on factors such as rainfall intensity and watershed
management practices. There have been numerous reports addressing siltation at Salinas Reservoir,
but no studies have been done for Whale Rock Reservoir.
Table 5 lists the studies for Salinas Reservoir and the estimated storage capacities. During the recent
drought, water at Salinas Reservoir fell to record low levels. Recognizing the unique opportunity
presented by the low water level, the County contracted with a local engineering consultant to
provide an aerial survey of the lake and prepare revised storage capacity information. The latest
information reveals that the survey conducted in 1975 may have over estimated the siltation rate at
the reservoir. Early studies indicated average annual siltation rates from 23 acre-feet per year to 34
acre-feet per year. The study done by the U.S. Geological Survey in 1975 estimated that the siltation
rate was approximately 82 acre-feet per year. The latest information indicates that the siltation rate is
on the order of 40 acre-feet per year.
Since Whale Rock is used as a backup supply for the City, it may be many years until the lake level
drops to the point where an aerial survey of siltation can be economically performed. Since no
information is available to indicate what rate of siltation is occurring at the Whale Rock Reservoir, it
is assumed for planning that the annual average rate of siltation is similar to Salinas Reservoir. New
water supply opportunities can be utilized to offset the long term siltation losses, as discussed
elsewhere in this document.
The safe annual yield from the two reservoirs will be continually reduced as a result of siltation. The
City's computer model can be used to calculate the reduction in safe annual yield from Salinas and
Whale Rock reservoirs to date. The model can then be used to calculate estimated annual reductions
in the future assuming siltation occurs in an average pattern.
Since the storage capacity for Salinas Reservoir was last estimated in 1990, the annual loss of 40
acre-feet per year can be applied from that date. However, since siltation at Whale Rock Reservoir
has never been factored into the total available water storage, the loss of 40 acre-feet per year would
apply to the period since the reservoir was constructed in 1961.
31
City of SLO General Plan Water & Wastewater Management Element
TABLE 5
SALINAS RESERVOIR CAPACITY STUDIES
The estimated loss in storage capacity for Salinas Reservoir between 1990 and 2000 is 400 acre-feet.
The estimated loss at Whale Rock Reservoir between 1961 and 2000 is 1,560 acre-feet. Based on
these reduced storage capacities, the computer model projects a loss of 250 acre-feet of safe annual
yield from the combined operation of the two lakes. With an estimated loss of 40 acre-feet per year
at each reservoir, the total safe annual yield from the two lakes will be reduced by 10 acre-feet per
year. This loss of yield is accounted for in the adopted safe annual yield figures shown in Table 1.
6.0 SUPPLEMENTAL WATER REQUIREMENTS
6.1 POLICIES
6. 1.1 Supplemental Water Requirement
The City shall develop additional water supplies to provide for the Primary Supply Requirements
identified below, and strive to develop additional water supplies to provide for the Secondary Supply
Requirements identified below, in the consideration of available water supply opportunities.
1. Primary Supply Requirements — Develop supplemental water supplies to provide sufficient
water for General Plan build -out using the per -capita planning use rate identified in Policy 3.1.2
multiplied by the projected General Plan build -out population, and
2. Secondary Supply Requirements —Develop supplemental water supplies to provide additional
yield to account for future siltation losses, drought contingency, loss of yield from an existing supply
10
Total
Usable
Avg Annual Loss
Year
Agency
Capacity
Capacity
Usable Capacity
(acre-feet)
(acre-feet)
(acre-feet/year)
1941
U.S. Army
44,800
26,000
-
1947
U.S. Soil Conservation
-
25,860
23.3
Service
1953
U.S. Soil Conservation
Service and U.S. Forest
-
25,590
34.2
Service
1975
U.S. Geologic I SurveyT41,400
23,200
82.4
1990
Count of San Luis Obispo
41,791
24,035
40.1
Usable capacities are shown at the 1,301.0 -foot spillway elevation because the usable capacity at the 1,300.7 -
foot elevation for the 1947 and 1953 studies could not be accurately determined. Usable capacity at the
1;300.7 -foot elevation for the 1941 survey was determined to be 25,800 acre-feet and for the 1975 survey was
23,000 acre-feet.
The estimated loss in storage capacity for Salinas Reservoir between 1990 and 2000 is 400 acre-feet.
The estimated loss at Whale Rock Reservoir between 1961 and 2000 is 1,560 acre-feet. Based on
these reduced storage capacities, the computer model projects a loss of 250 acre-feet of safe annual
yield from the combined operation of the two lakes. With an estimated loss of 40 acre-feet per year
at each reservoir, the total safe annual yield from the two lakes will be reduced by 10 acre-feet per
year. This loss of yield is accounted for in the adopted safe annual yield figures shown in Table 1.
6.0 SUPPLEMENTAL WATER REQUIREMENTS
6.1 POLICIES
6. 1.1 Supplemental Water Requirement
The City shall develop additional water supplies to provide for the Primary Supply Requirements
identified below, and strive to develop additional water supplies to provide for the Secondary Supply
Requirements identified below, in the consideration of available water supply opportunities.
1. Primary Supply Requirements — Develop supplemental water supplies to provide sufficient
water for General Plan build -out using the per -capita planning use rate identified in Policy 3.1.2
multiplied by the projected General Plan build -out population, and
2. Secondary Supply Requirements —Develop supplemental water supplies to provide additional
yield to account for future siltation losses, drought contingency, loss of yield from an existing supply
10
City of SLO General Plan Water & Wastewater Management Element
source, operational requirements necessary to meet peak operating demands, and other unforeseen
conditions.
6.1.2 Supplemental Water Sources
In deciding appropriate sources of supplemental water, the City will evaluate impacts on other users
of the water and other environmental impacts, total and unit costs, reliability, water quality,
development time, and quantity available.
6.13 Paying for Supplemental Water for New Development
The cost for developing new water supplies necessary for new development will be paid by impact
fees set at a rate sufficient to cover the annual debt service cost of the new water supplies attributable
to new development.
BACKGROUND
Based on the Land Use Element adopted by the City Council in August 1994 and a per capita use
rate of 145 gallons per person per day, the projected total amount of water for the City to serve
General Plan build -out is 9,096 acre-feet. Many of the Secondary Supply Requirements identified in
Policy 6. 1.1 are unquantifiable at this time, and their development should be considered by Council
in the review of new water supply opportunities.
TABLE 6
REQUIRED SAFE ANNUAL YIELD
FOR GENERAL PLAN BUILD -OUT
Source of Demand
Population
Acre-feet
(at 145 gal per
day rperson)
Percent
of Total_
Existing (2002) Development
44,426
7,216
79.3%
New Development
11,574
1,880
20.70/c
TOTAL
56,000
9,096
100.00
City policy adopted in 1987 as part of the Water Element states that the costs of developing
supplemental water sources will be borne by those making new connections to the water system.
Policy 6.1.3 continues this policy and is consistent with the Land Use Element (policy 1.13.4.)
1.1
City of SLO General Plan Water & Wastewater Management Element
7.0 MULTI -SOURCE WATER SUPPLY
7.1 POLICY
7.1.1 Multi -Source Water Supply
The City shall continue to develop and use water resources projects to maintain multi -source water
supplies, and in this manner, reduce reliance on any one source of water supply, to provide for peak
operating demands in the event one of the City's major water supply sources is unavailable, and to
increase its supply options in future droughts or other water supply emergencies.
BACKGROUND
Having several sources of water can avoid dependence on one source that would not be available
during a drought or other water supply reduction or emergency. There may be greater reliability and
flexibility if sources are of different types (such as surface water and ground water) and if the sources
of one type are in different locations (such as reservoirs in different watersheds).
The Water Element of the General Plan, adopted in 1987, identified multiple water projects to meet
projected short and long term water demand. In November of 1990, the Council again endorsed the
multi -source concept.
8.0 ALLOCATION OF NEW WATER SUPPLIES
8.1 POLICIES
8.1.1 Balancing Safe Yield and Overall Demand
When new water sources are obtained, the additional safe yield shall be allocated first to eliminate
any deficit between the adopted safe annual yield (Section 1.0) and the present demand as defined in
Policy 3.1.4, second to eliminate any deficit between adopted safe yield and General Plan build -out,
and third to supply for the Secondary Supply Requirements as identified in Policy 6.1.1.
8.1.2 Supplying New Development
A. The City will determine the water available for allocation to new development by either; the
adopted safe annual yield of the City's water supplies minus present demand as identified in
Policy 3.1.4, or the projected demand at build -out as identified in Policy 3.1.3 minus.present
demand as identified in Policy 3.1.4; whichever is less. Available allocations will be assigned to
development in a way that supports balanced growth, consistent with the General Plan.
Allocations from a new water supply project shall be considered available at the time project
construction is initiated.
B. Any safe annual yield from new water supply projects beyond that needed to balance safe annual
yield and present demand will be allocated to development, subject to the requirements in Policy
8.1.3, "Reserve for Intensification and Infill."
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City of SLO General Plan Water & Wastewater Management Element
C. A water allocation shall not be required for projects for which the developer makes changes in
facilities served by the City that will reduce long-term water usage equal to twice the water
allocation required for the project.
8.1.3 Reserve for Intensification and Infill Development
The City will annually update the water available for allocation based on the difference between the
adopted safe annual yield (policy 1. 1.2) and the present water demand (policy 3.1.4) as part of the
annual Water Resources Status Report. One-half of the water available for allocation (not to exceed
the total required for infill and intensification), as identified in the Water Resources Status Report,
will be reserved to serve intensification and infill development within existing city limits as of July
1994.
8.1.4 Accounting for Reclaimed Water
Reclaimed water has an estimated potential of 1,200 acre feet per year of water available for
appropriate non -potable uses. The amount to be added to the City's safe annual yield, and therefore
available for development, will only be the amount projected actually to be used or offset
(approximately 130 a.f. initially), increasing to 1,200 acre feet per year as additional offsetting uses
are brought on-line. The amount of reclaimed water used each year will be reported to Council as
part of the annual Water Resources Status Report and will be added to the safe annual yield
identified in Section 1, Table 1 of this document to determine water available for new development.
8.15 Private Water Supplies
When developments are supplied by private groundwater wells, the yield of those wells will not be
counted toward the City's safe annual yield. Such yield, however, will result in the demand for City
water supplies being lower than it otherwise would be, which may necessitate adjustments of the per
capita water usage figure used to estimate overall demand.
BACKGROUND
The City has pursued numerous water supply projects over the years. (These projects are discussed
in Chapter 3 of the Urban Water Management Plan.) This part of the element addresses allocation of
these supplies once the yields from projects are realized. The City has identified these potential uses
for new supplies:
■ Eliminating any deficit between adopted planning figures and safe annual yield;
■ Providing for water requirements for future development within the urban reserve area
designated in the General Plan;
■ Compensating for reduced yields due to reservoir siltation;
■ Providing additional water supplies, as determined by Council, for drought, operational
requirements for meeting peak demands, and other water supply emergencies;
■ Providing water for habitat management.
Allocation of new supplies can balance the needs of all areas identified while not compounding the
potential water shortage problems for existing City water customers.
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City of SLO General Plan Water & Wastewater Management Element
The adoption of 145 gallons/per person/per day as a water supply planning figure would indicate
water is available for development, eliminating the need for retrofitting. Because 145 gallons/per
person/per day assumes that the retrofit component of the water conservation program is complete,
new development will continue to retrofit until the entire city is essentially retrofitted as determined
by the City Council.
9.0 WATER ALLOCATION AND OFFSETS
9.1 POLICIES
9.1.1 Exemptions for Offsets
A. The City will not allow a project to reduce or eliminate the amount of the required allocation or
offset, to the extent that the project is supplied by a private well, with the following exceptions:
The City may reduce the amount of the required water allocation, to the extent that the
project is supplied by a private well serving non -potable water needs (such as irrigation)
which will not significantly affect the yield of City wells: Such a well may be operated by
the owner of the property containing the well only for the owner's use. As an exemption, the
City may allow a well to supply landscape irrigation on more then one parcel if the irrigation
is:
a. for the common area of a condominium complex or other developments with similar
common areas as approved by the Utilities Director, and the well and irrigation
system are under the control of an owner's association; or
b. in a single commercial development, and the well and irrigation system are subject to
a recorded agreement among parcel owners, which is acceptable to the Utilities
Director and the City Attorney, and which establishes responsibilities for operation
and maintenance of the common areas served by the well.
2. When an allocation or potential offset is not available, a well maybe allowed to eliminate the
required offset for potable water needs only as an interim source until a new City water
source is available. Once a new source becomes available, the project will be required to
acquire an allocation from the City. Impact fees will be due at the time the development is
approved.
3. The City Council approves the well proposal as part of a specific land development project
approval, and the proposed well system meets all City standards; and
4. A qualified, independent, hydrological investigation demonstrates that the well(s) reliably
can provide sufficient quality and quantity of water for the proposed land development
project and will not impact the yields from City wells.
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City of SLO General Plan Water & Wastewater Management Element
9.1.2 Basis for Allocations and Offsets
Required allocations and offsets will be based on long-term usage for each type of development.
(These use and offset factors will be determined and published by the City, and may be revised, as
warranted, by new information.)
BACKGROUND
In 1988, the City began to formally account for long-term water usage in new development. The
allocations have been based on histories of water usage for various kinds of development. At first,
the City decided to allocate some water for new land development projects even though city-wide
water usage exceeded safe yield. As the 1986-1991 drought continued, and the projected completion
of proposed supplemental supply projects moved farther into the future, the City decided that there
should be no new development that would increase water usage. As a result, nearly all construction
since 1990 has been:
■ Replacement buildings, using the same or less water;
■ Additions or remodels which do not substantially affect water usage; and
■ Projects that have retrofitted facilities served by the City, to save (offset) twice the amount of
water that would be allocated to the project. Installation of low -flow toilets, showerheads, and
faucets have accounted for most of the offset credit. Substantial credits were also earned by
installing water -recycling equipment in businesses.
Also, a few relatively small projects were able to do little or no retrofitting because they were
supplied with groundwater through private wells. Some projects have utilized more than one of
these strategies to proceed despite the lack of water allocations.
10.0 RECLAIMED WATER
10.1 POLICIES
10.1.1 Reclaimed Water Quality
The City will produce high quality reclaimed water, suitable for a wide range of nonpotable uses.
10.1.2 Uses of Reclaimed Water
The City will make available reclaimed water to substitute for existing potable water uses -as allowed
by law and to supply new nonpotable uses.
When deemed appropriate by the Utilities Director, new development shall be equipped with dual
plumbing to maximize the use of reclaimed water for non -potable uses.
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City of SLO General Plan Water & Wastewater Management Element
BACKGROUND
Reclaimed water is highly treated wastewater (sewage) which can be used for most nonpotable
purposes. The City's Water Reclamation Facility (formerly known as the Wastewater Treatment
Plant) has been upgraded to the point the effluent can be used directly for landscape and agricultural
irrigation and other uses such as industrial processes and toilet flushing in certain types of buildings.
Most treated effluent, in the past, has been discharged to San Luis Obispo Creek. A small amount of
effluent has been used at the treatment plant site for landscape irrigation. Reclaimed water will be
used for additional landscape irrigation at the Water Reclamation Facility and on City -owned land in
the vicinity, and for ponds to benefit wildlife.
Use of reclaimed water beyond the treatment plant area will require a distribution system separate
from other water lines. Reclaimed water can be used to supply nonpotable uses in new development
and to offset potable uses in existing development. These potential uses require a deliberate method
to account for reclaimed water use, consistent with policies concerning total water requirements and
other water sources.
Long-term funding for the necessary reclaimed water distribution system is expected to come from
charges for the use of reclaimed water. Initial expenses may be funded from bonds, low-interest State
loans, and developer contributions.
11.0 WATER SERVICE WITHIN THE CITY
11.1 POLICY
11.1.1 Water Service within the City
A. The City will be the only purveyor of water within the City.
B. Appropriate use of privately owned wells may be allowed with the approval of the Utilities
Director, consistent with policies 8.1.5 and 9.1.1.
BACKGROUND
Historically, the City has been the sole water purveyor within the City limits. This allowed the City
to maintain uniformity of water service and distribution standards, and to be consistent in developing
and implementing water policy. In continuing to be the sole water purveyor, the City will maintain
control over water quality, distribution and customer service, as well as ensure consistency with the
City's General Plan policies and goals.
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City of SLO General Plan Water_& Wastewater Management Element
WASTEWATER SECTION
GOAL
San Luis Obispo's wastewater goal is to provide efficient and environmentally acceptable wastewater
disposal service for the community.
12.0 SERVICE AREA AND POPULATION
12.1 POLICIES
12.1.1 Service Area
The current wastewater service area is the incorporated area of the City. The City shall provide
wastewater service adequate for existing uses and new development pursuant to the Land Use
Element for all areas within the city limits.
12.1.2 Areas Within the Urban Reserve Line
The urban reserve line (the outer limit to urban development) includes areas which the City may
annex in the future. Wastewater service adequate for potential uses allowed by the Land Use
Element (including hillside planning provisions) shall be provided for all areas within the urban
reserve line.
12.13 Service Outside the City Limits
To receive City wastewater service, areas must be annexed to the city. The City will not provide
wastewater service for areas outside the city limit, except for:
A. Customers which have prior agreements.
B. Uses which are consistent with the General Plan and which are located on areas of less than
one acre, which are surrounded on at least three sides by areas that are already served.
12.1.4 Areas Outside the Urban Reserve Line
The City will not provide wastewater service to areas outside the urban reserve line.
12.1.5 Special Districts
Special districts should not provide wastewater service within the City's planning area to uses
inconsistent with the City's General Plan.
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City of SLO General Plan Water & Wastewater Management Element
12.1.6 Service Capacity
The City's wastewater collection and treatment systems must be able to support population and
related service demands consistent with General Plan objectives. These basic objectives are stated in
the Land Use Element (growth management) and in the Housing Element.
12.1.7 Annexation Criteria
The City will not annex an area unless it can meet the wastewater treatment needs of the area to be
annexed, in addition to the wastewater treatment requirements for all development, consistent with
the land Use Element, within the city including the annexed area. The only exceptions to this policy
are:
A. Areas which have prior agreements for wastewater service.
B. Minor infill parcels within areas which have prior agreements for wastewater service, as
provided in policy 12.1.3.
12.2 PROGRAMS
12.2.1 Updates
The City will update this element's service area description and population projections as needed and
in concert with any amendments to the Land Use Element.
Time frame: continuing
Responsible parties: Community Development Department; Planning Commission, City Council.
Funding: City general fund
12.2.2 Projections of Requirements
The City will refine this element's projections of wastewater treatment requirements on the basis of
wastewater flows from specific land use categories and the likely development of those categories as
provided in the Land Use Element.
Time frame: Following adoption of the Land Use Element update.
Responsible parties: Community Development Department; Utilities Department; Planning
Commission; City Council.
Funding: City general fund.
12.2.3 Expanding Capacity
The City will expand the capacity of the wastewater treatment plant to provide adequate treatment
for projected wastewater flows.
Time frame: Late 1980's to late 1990's.
Responsible parties: Utilities Department; City Council.
Funding: Development and connection charges, wastewater fees, and grants.
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City of SLO General Plan Water& Wastewater Management Element
13.0 WASTEWATER COLLECTION, TREATMENT, AND DISPOSAL
13.1 POLICIES
13.1.1 Stormwater Infiltration
The City will minimize stormwater infiltration into the sewer system.
13.1.2 System Protection
The City will minimize damage to the wastewater collection and treatment systems by preventing
discharge of materials that are toxic or which would obstruct flows.
13.13 Managing Treatment Demand
The City will manage wastewater treatment demand to assure that it can provide a high level of
wastewater service.
13.1.4 Beneficial Use
The City will pursue treatment and disposal methods which, to the maximum extent feasible, provide
for further beneficial use of wastewater and allow beneficial uses of land or water receiving the
effluent.
13.15 City as Exclusive Provider
The City will be the only provider of public wastewater treatment within the City (but on-site
pretreatment of wastewater to meet City Standards may be required).
13.1.6 Energy Efficiency
Wastewater operations will minimize energy use and will incorporate cost-effective energy recovery
or production facilities.
13.2 PROGRAMS
13.2.1 Reducing Infiltration
The City will continue to investigate and carry out cost-effective methods for reducing stormwater
flows into the wastewater system.
Time frame: Continuing
Responsible agencies: Utilities Department; City Council
Funding: Wastewater revenues
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City of SLO General Plan Water & Wastewater Management Element
13.2.2 Discharge Standards
The City will update and enforce its standards for the quality of wastewater discharged to the system.
Time frame: Continuing
Responsible agencies: Utilities Department; City Council
Funding: Wastewater revenues
13.2.3 Project Evaluation
The City will continue to evaluate the potential for the wastewater flows of a proposed project to
exceed the capacity of collection and treatment systems.
Time frame: Continuing
Responsible agencies: Utilities Department;
Council
Funding: General fund
Community Development Department; City
13.2.4 State and Federal Water Quality Standards
The City will change its treatment and disposal practices in an attempt to meet federal and state
water -quality standards. The first step will be adoption of the Wastewater Management Plan and
completion of pre -design technical reports that will describe a specific strategy for treatment and
disposal. Any additional required environmental review would be integrated with the pre -design
work. Then, plans and specifications, and a budget, for the construction project would be prepared.
The timing of these steps will be worked out in collaboration with the Regional Water Quality
Control Board.
Time frame: Construction complete in the early 1990's
Responsible agencies: Utilities Department; City Council
Funding: Wastewater revenues; state or federal grants
14.0 WASTEWATER REVENUES AND FINANCING
14.1 POLICY
14.1.1 Enterprise Activity
The City's wastewater system will be operated as an enterprise activity, with costs to be borne by
wastewater fees and charges. Costs of operating, maintaining, and replacing the wastewater system
will be borne by all customers. Some portion of the costs of making major decisions about the
wastewater systems --such as evaluating changes to citywide collection and treatment-- may be borne
by the whole community. Costs of expanding treatment capacity and extending the collection system
to serve new development shall be borne by those making new connections to the system, in
proportion to expected wastewater flows. The City will seek any state or federal grants which may
be available to fund sewer system improvements. Programs to fund wastewater projects should be
consistent with the growth management policies of the General Plan.
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City of SLO General Plan Water & Wastewater Management Element
14.2 PROGRAM
14.2.1 Revising Charges
The City will periodically revise its schedule of charges for wastewater service. The city will prepare
a development fee schedule to fund expansion of collection and treatment facilities.
Time frame: Periodic rate evaluation; development fees to be adopted by July 1988 and updated
as required.
Responsible parties: City staff; City Council.
WASTEWATER BACKGROUND
Current Wastewater Flows and Treatment
The City is responsible for collecting, treating, and disposing of wastewater from about 19,000
residential, commercial, industrial, and public customers every day, in a way that avoids
environmental and public health problems. In addition to homes and businesses within the city
limits, the City provides wastewater services for Cal Poly and the County airport.
The City's existing wastewater collection system partly determines the character of wastewater flows.
About 150 miles of sewer pipes, ranging from six to 30 inches in diameter, collect wastewater
flows. The oldest pipes date from the 1890's, when pipe materials and trenches were less able to
withstand the effects of corrosion and soil settlement.. Eight pumping stations move the wastewater
from areas where the slope of sewer pipes is not sufficient to allow gravity flow. Sewer lines cross
creeks at 95 locations in the City; at some locations, siphons (U-shaped sections of pipe) allow the
flows to continue. In some places, newer pipes have been installed parallel to older pipes to handle
increased flows.
Despite the City's efforts to repair and replace older and deteriorated sewer pipes, some cracked
joints between pipe sections, some manhole covers, and improperly connected storm -water drains
allow water from rainfall and saturated ground to enter the sewage collection system. This storm -
water infiltration significantly increases the amount of wastewater that must be treated during the wet
season. Undersized and damaged lines, siphons, and parallel pipes are often the source of wastewater
collection problems.
Collected flows are treated at the City's plant on Prado Road near Highway 101. The plant removes
floating and large, gritty material, reduces the amount of nutrients and bacteria, separates sludge
from the waste stream, and discharges the effluent into San Luis Obispo Creek near Los Osos Valley
Road. Sludge is separated from the wastewater, dried in open ponds at the treatment plant, and
hauled away for use on landscaping or crops. While the treatment plant uses tanks, pumps, and other
mechanical equipment, most of the wastewater treatment is actually done by living microorganisms.
The man-made features are largely to provide a suitable place for them to grow.
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City of SLO General Plan Water & Wastewater Management Element
Wastewater flows are measured in millions of gallons per day --abbreviated "mgd." (One million
gallons would fill a tank 60 feet in diameter and 50 feet high.) In 1986, the average flow into the
treatment plant during dry weather was 4.4 mgd. During wet weather, the peak flow was 22.4 mgd.
Standards for quality of the treated effluent follow from federal and state water -quality laws. The
specific requirements for San Luis Obispo were most recently set by the state's Regional Water
Quality Control Board in April 1986. The standards are to protect present and potential beneficial
uses of the water which receives the effluent, including recreation, agricultural supply, and fish and
wildlife habitat. The standards include:
For the creek -maximum allowed changes in acidity/alkalinity, temperature, and oxygen;
• For the effluent - maximum allowed quantities of solid particles and dissolved solids,
nutrients which deprive the water of oxygen through chemical and biological action, oil and
grease, coliform bacteria, and chlorine left from the last treatment step.
Effluent quality has violated the standards, so the Regional Water Quality Control Board has ordered
the City to improve the effectiveness of its treatment. The primary problem has been the amount of
nitrogen in the form of ammonia. Other nutrients, suspended solids, oil and grease, and coliform
bacteria have also exceeded the standards.
Projected Wastewater Flows
If the City grows to about 53,000 population in the year 2015, as outlined in the Land Use Element,
the average dry -weather volume of wastewater is expected to increase by about 32 percent, from 4.4
mgd to 5.8 mgd. Other measures of required treatment capacity, such as flow in the peak month and
the amount of nutrients and solids, are expected to increase in about the same proportion.
Consulting engineers have concluded that the existing wastewater treatment plant site is big enough
for a plant to handle the projected flows, but the treatment plant will have to be changed to treat such
flows effectively. The City plans a two -phased expansion of treatment capacity. The first phase
would also improve the effectiveness of treatment. Both phases involve changing and enlarging
certain facilities at the treatment plant
Alternative Treatment and Disposal Methods
Many different methods of disposing of treated wastewater (effluent) have been considered. Each
method has its own advantages and disadvantages. In evaluating treatment and disposal methods, the
City will consider initial and continuing costs, environmental impacts, reliability, flexibility, and
potential for increasing beneficial uses of treated wastewater. Preliminary evaluations have indicated
that some of the options listed below are not feasible or cost-effective. The feasibility and desirability
of others will not been known until additional evaluations are completed, and even then changing
conditions may warrant reconsideration or further study.
The City does not want to preclude treatment and disposal options which may turn out to be feasible.
However, the City must select an overall strategy for treatment and disposal and begin to carry it out,
in order to meet established water -quality standards. Once a strategy is chosen and money is
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City of SLO General Plan Water & Wastewater Management Element
committed to certain physical projects, those funds would not be available to spend on significantly
different strategies.
Several alternatives to conventional stream disposal, which could be used in various combinations,
are briefly described below. With the exception of an ocean outfall, each alternative involves some
beneficial use --reclamation-- of the treated wastewater, as does direct stream disposal (which helps
maintain stream habitat and recharges downstream wells). Reclaiming all the effluent for uses that
would otherwise need fresh City water, which is not likely in the time frame of this element, would
displace the need for about 5,000 acre-feet of water in 1987, and about 6,600 acre-feet in 2015.
Irrigation
Effluent could be used to irrigate recreational land (such as a golf course) or agricultural land.
Effluent used for pasture irrigation would probably not have to meet standards as high as those
for creek disposal. However, to dispose of all projected effluent quantities during all seasons, the
City would have to own or permanently control the use of about 2,000 acres of land. Even with
availability of such a large area for irrigation, a substantial holding pond would be required for
winter storage, when the ground is saturated. The main obstacles to this approach are obtaining
the required disposal area, piping the effluent to it, and assuring no long-term harm to soil
characteristics or groundwater supplies. Effluent used to irrigate landscaping or recreational land
could replace water from other sources, or it could enable expansion of landscaped or
recreational areas without drawing on limited supplies of fresh water.
Stream Improvement
The creek's ability to provide good wildlife habitat can be improved in ways other than removing
certain contaminants from the effluent. Effluent, possibly with more nutrients or discoloring
substances than now allowed, could be discharged at several points within an enlarged
streamside forest. Additional streamside trees and plants (a riparian corridor) would help remove
nutrients. They would also shade the water, and could therefore help keep it cooler. Along with
using such natural treatment capacity, the City could restore some of the habitat downstream
from the treatment plant, which has been harmed by vegetation removal and intensive livestock
use. The City's improving the habitat might allow relaxation of some discharge standards, since
creation of a riparian corridor would enhance a beneficial use which the Regional Water Quality
Control Board is trying to protect.
Groundwater Recharge
If suitable areas could be found and used by the City,. effluent could be deliberately spread to
percolate into the ground to recharge aquifers. While stream disposal does this for some
downstream areas, disposal at other locations might allow more of the water to be retained where
it could be withdrawn efficiently for use by the City.
Laguna Lake or Marsh
Effluent could be used to maintain a fairly constant level of Laguna Lake year-round. Much of
the effluent would still make its way to San Luis Obispo Creek. If the effluent entered the lake
directly, the required level of treatment would exceed that for direct stream disposal, since the
lake is used for water -contact sports. Discharging the effluent into the marsh at the northerly end
of the lake, or as pasture or landscape irrigation, would allow some natural filtering and might
require a lower level of treatment than direct stream disposal.
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City of SLO General Plan Water & Wastewater Management Element
Industrial Reuse
Some industries use large quantities of water that need not be of drinking quality. San Luis
Obispo does not have significant manufacturing or processing industry, though it does have some
businesses, such as laundries, which might be able to use properly treated effluent. Such effluent
as a source of water also might enable industries that could not otherwise locate in San Luis
Obispo to do so.
Aquaculture
Sewage is basically heavily fertilized water. If proper growth conditions are provided and
harmful substances are controlled, the water -borne nutrients can be converted to useful plants
and animals through aquaculture. Water hyacinth (used to produce methane, soil conditioner, or
livestock feed) and several varieties of fish have been produced in municipal wastewater
treatment plants. Difficulties with this approach include finding and maintaining markets for the
products and continuously providing acceptable levels of treatment with widely varying
wastewater flows and weather conditions.
Domestic Reuse
With substantially higher levels of treatment than now used and a suitable distribution system,
wastewater could provide for the full range of household uses. However, meeting state and
federal standards for quality of drinking water would be very difficult. The costs of adequate
treatment and distribution, even for household landscape irrigation, far exceed other alternatives
and are expected to be prohibitive for the foreseeable future.
Ocean Outfall
Coastal communities dispose of their effluent in the ocean. San Luis Obispo could pipe its
treated effluent to San Luis Bay. However, the costs of building and maintaining a pipeline to the
ocean appear greater than the savings that might be achieved through meeting the somewhat
lower effluent standards for ocean disposal. Coastal Commission approval would be required for
an ocean outfall.
Wastewater Costs and Revenues
The City budgets its wastewater activities separately from other City services and has a long-standing
policy that wastewater revenues should fully fund wastewater services. Those making new
connections to the sewer system pay for some of the cost of developing the existing system.
Residential customers and most small businesses are billed at a uniform monthly rate, while some
larger businesses pay according to the amount of water they use. In 1986-87, the City sewer system
budget was $1.1 million.
To fund anticipated treatment -plant and collection -system changes through the 1990's, the City
probably will need to substantially increase sewer rates, even with federal grant funding. Also,
federal rules may require the City to revise its rate structure, so users are charged according to the
average and peak quantities and concentration of contaminants of the wastewater they produce.
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