HomeMy WebLinkAboutAppendix M-Water Supply AssessmentAPPENDIX M
Water Supply Assessment
Avila Ranch Development Project
Final EIR
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WATER SUPPLY ASSESSMENT
Water Code §10910 et seq.
[Plan for acquiring and developing
sufficient supply attached. Water Code§ 10911 (a)].
X
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Table of Contents
Table of Contents ........................................................................................................................................ ii
Tables ........................................................................................................................................................ iii
Appendices ................................................................................................................................................. iii
1.INTRODUCTION .............................................................................................................................. 1
1.1 Background ...................................................................................................................................... 1
1.2 Project Location and Description ..................................................................................................... 2
2.WATER SUPPLY ............................................................................................................................. 2
2.1 Surface Water Supply: ..................................................................................................................... 2
2.2 Recycled Water Supply: ................................................................................................................... 3
2.3 Groundwater Supply: ....................................................................................................................... 3
3.URBAN WATER MANAGEMENT PLAN APPLICABILITY ........................................................... 4
4.WATER RESOURCE AVAILABILITY ............................................................................................. 4
5.WATER SUPPLY RELIABILITY ..................................................................................................... 5
6.WATER USAGE .............................................................................................................................. 6
6.1 Water Conservation Program: ......................................................................................................... 6
7.ENTITLEMENTS/REGULATORY APPROVALS ............................................................................ 8
8.AVILA RANCH PROJECT .............................................................................................................. 8
9.CONCLUSION ............................................................................................................................... 11
REFERENCES ............................................................................................................................................ 12
TECHNICAL APPENDICES ....................................................................................................................... 13
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Tables
Table 4-1. City Water Resource Availability ............................................................................................. 5
Table 4-2. City Non-Potable Water Resource Availability ....................................................................... 5
Table 5-1. Water Supply Reliability ........................................................................................................... 6
Table 5-2. 2014 City Water Supply Availability ........................................................................................ 6
Table 8-1. Avila Ranch Water Demand – Project Specific ...................................................................... 9
Table 8-2. Avila Ranch Project Water Demand by Use Factors ........................................................... 10
Table 8-3. City Water Supply Availability and Avila Ranch Water Usage ........................................... 10
Appendices
Appendix A: Preliminary Irrigation Water-Use Estimate
Appendix B: Avila Ranch Recycled Water Use Areas
Appendix C: Airport Area Specific Plan: Water Conservation Policy 7.2.2
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1. INTRODUCTION
This water supply assessment is provided for the proposed Avila Ranch for the City of San Luis
Obispo, pursuant to the requirements of Section 10910 of the State Water Code, as amended
by Senate Bill No. 610, Chapter 643 (2001).
1.1 Background
Senate Bill No. 610, effective January 1, 2002, requires a city or county, which determines that
a “project” (as defined in Water Code§ 10912) is subject to the California Environmental Quality
Act (CEQA), to identify any public water system that may supply water for the project and to
request those public water systems to prepare a specified water supply assessment. The
assessment is required to include an identification of existing water supply entitlements, water
rights, or water service contracts relevant to the identified water supply for the proposed project
and water received in prior years pursuant to those entitlements, rights, and contracts. The
assessment must be approved by the governing body of the public water system supplying
water to the project. If the projected water demand associated with the project was included as
part of the most recently adopted urban water management plan, the public water system may
incorporate the requested information from the urban water management plan in the water
supply assessment. The bill requires the city or county, if it is not able to identify any public
water system that may supply water for the project, to prepare the water supply assessment
after a prescribed consultation. If the public water system concludes that water supplies are, or
will be, insufficient, plans for acquiring additional water supplies are required to be submitted to
the city or county. The city or county must include the water supply assessment in any
environmental document prepared for the project pursuant to the act. It also requires the city or
county to determine whether project water supplies will be sufficient to satisfy the demands of
the project, in addition to existing and planned future uses.
A “project” under Section 10912 includes the following:
a. A proposed residential development of more than 500 dwelling units.
b. A proposed shopping center or business establishment employing more than 1,000
persons or having more than 500,000 square feet of floor space.
c. A proposed commercial office building employing more than 1,000 persons or having
more than 250,000 square feet of floor space.
d. A proposed hotel or motel, or both, having more than 500 rooms.
e. A proposed industrial, manufacturing, or processing plant, or industrial park planned to
house more than 1,000 persons, occupying more than 40 acres of land, or having more
than 650,000 square feet of floor area.
f. A mixed-use project that includes one or more of the projects specified in this
subdivision.
g. A project that would demand an amount of water equivalent to, or greater than, the
amount of water required by a 500 dwelling unit project.
The Avila Ranch project includes at least 500 units and 15,000 square feet of shopping center
area, and the SB610 requirements apply to the project.
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1.2 Project Location and Description
The proposed Avila Ranch is located in the City of San Luis Obispo along the north side of
Buckley Road, extending from Vachell Lane to approximately 4,000 feet to the east, and
approximately 2,000 feet to the north. The site consists of over 150 acres of property zoned for
Business Park uses that will be developed into over 700 dwelling units and several land use
categories; therefore, the requirements of Section 10910 of the California Water Code apply to
the proposed project. The property was annexed to the City in 2008 and is covered by the
City’s UWMP and Water and Wastewater Element.
2. WATER SUPPLY
Water Code Section 10910(b) requires the identification of the public water system that may
serve the project. The City is the sole water purveyor within the city limits and will provide water
to the proposed Avila Ranch. The City’s water is supplied from multiple surface water sources,
in addition, to recycled water and groundwater to supplement irrigation demands.
The Water and Wastewater Element of the General Plan, first adopted in 1987 and most
recently updated in 2010, specifies that the City utilize multiple water resources to meet its
water supply needs. Having several sources of water avoids dependence on any one source
that may not be available during a drought or other water supply reduction or emergency. With
the update of the Water and Wastewater Element, the City Council reaffirmed the policy for a
multi-source water supply. Consistent with the multi-source water supply concept, the City
obtains water from five sources:
• Salinas Reservoir (Santa Margarita Lake) and Whale Rock Reservoir: Combined Safe
Annual Yield 6,940 acre-feet (AF)/year
• Nacimiento Reservoir: 3,380 AF/year dependable yield/ contractual limit
• Recycled water from the City’s Wastewater Reclamation Facility (WRF): potentially 1,000
AF/year available
• Groundwater: Supplemental usage, 100 AF/year in 2011
2.1 Surface Water Supply:
The Salinas Dam was built in 1942 by the War Department to supply water to Camp San Luis
Obispo and secondarily, to meet the water needs of the City of San Luis Obispo. The Salinas
Reservoir (Santa Margarita Lake) captures water from an 112 square mile watershed and can
store up to 23,843 AF. Since the late 1940s, the San Luis Obispo County Flood Control and
Water Conservation District has operated the Salinas Reservoir under a lease from the U.S.
Army Corps of Engineers. Water from the reservoir is pumped through the one mile long Cuesta
Tunnel, and then flows by gravity to the City’s Water Treatment Plant on Stenner Creek Road.
The Whale Rock Reservoir is a 40,662 acre foot reservoir created by the construction of an
earthen dam on Old Creek near the town of Cayucos. The Whale Rock Dam captures water
from a 20.3 square mile watershed and water is delivered through 17.6 miles of 30 inch pipeline
and by two pumping stations. The City of San Luis Obispo owns 55.05 percent of the water
storage rights at the reservoir. The remaining water storage rights are divided between the two
State agencies with Cal Poly owning 33.71 percent and the California Men’s Colony owning
11.24 percent.
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The Nacimiento Reservoir provides flood protection and is a source of supply for groundwater
recharge for the Salinas Valley. It is owned and operated by the Monterey County Water
Resources Agency. Since 1959, the San Luis Obispo County Flood Control and Water
Conservation District has had an entitlement to 17,500 AF/year of water from the reservoir for
use in San Luis Obispo County. Approximately 1,750 AF/year have been designated for uses
around the lake, leaving 15,750 AF/year for allocation to other areas within the County of San
Luis Obispo.
2.2 Recycled Water Supply:
Recycled water was envisioned as part of the City’s overall water supply strategy since the
1980s. In 1994, the City began a major capital improvement project at the City’s Water
Reclamation Facility (WRF) that included addition of tertiary treatment and other unit processes
required to meet stringent effluent quality limits, set forth by the Regional Water Quality Control
Board, intended to protect and enhance the receiving waters of San Luis Obispo Creek. The
City completed construction of the Water Reuse Project in 2006 and recycled water deliveries
began in May that year. The main non-potable water source is the City’s WRF which has a
design flow rate of 5,700 AF/year (5.1 mgd). The City is required to release 1,807 AF/year of
flow to San Luis Creek for environmental enhancement. In 2013, recycled water was delivered
to 29 sites with total usage over 177 AF/year. Two new sites (American’s Tire and Mangano
Homes streetscape) since then have subsequently been connected to the city’s recycled water
distribution system to provide landscape irrigation. The recycled water usage for 2014 and
2015 totaled 185 AF/year and 168 AF/year, respectively. This is well below the WRF’s
maximum design capacity of approximately 2,800 AF/year (2.5 mgd). The Water Reuse project
has the potential to deliver 1,000 AF/year of recycled water for appropriate non-potable uses
including landscape irrigation, construction water for dust control and some industrial purposes.
2.3 Groundwater Supply:
The City's major source of water was groundwater and local creeks until 1944 when it began to
use water from Salinas Reservoir. As a result of the drought beginning in 1986 and decreasing
surface water supplies, the City activated groundwater wells in 1989 to meet water demand.
The principal source of groundwater for the city is the San Luis Obispo Groundwater Basin. The
basin is fifteen square miles and is drained by San Luis Obispo Creek. It extends from the
northern limits of the city and continues southerly along the alignment of the creek to just south
of Buckley Road. In the Los Osos Valley area, the basin extends four miles west to the Los
Osos Basin, which includes the community of Los Osos/Baywood Park.
In 1990, at the height of the drought, the City had seven potable wells that accounted for
approximately 50 percent of the water supplied during that period. The current groundwater
program uses one potable well, one non potable construction water well, and two irrigation
wells. Two other of the City's wells were shut down in 1992 and 1993 due to elevated nitrate
levels.
The majority of groundwater use from the San Luis Obispo Groundwater Basin is used for
agricultural purposes and private property uses. The basin has not been defined to be in
overdraft and has not been adjudicated. According to DWR’s Bulletin 118, the basin is relatively
small and recharges very quickly following normal rainfall years. Because of these factors, no
groundwater management plan has been prepared for the basin. In 2011, the City relied on
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groundwater to supply approximately two percent of the city’s annual water demand. The City
stopped the supply of groundwater to its drinking water system in April 2015 due to new
regulatory requirements that would require additional costly treatment of the wells before the
water could be used. The groundwater wells remain in operable standby condition should use
of groundwater be required in the future. The City no longer relies on groundwater for long term
community water demands because of water quality and reliability issues and does not consider
this source of supply as part of its water resources planning.
3. URBAN WATER MANAGEMENT PLAN APPLICABILITY
Water Code Section 10910(c)(1) requires a determination of whether or not the project was
included in the City’s most recently adopted Urban Water Management Plan (UWMP), adopted
on June 21, 2011. The UWMP provides a description of the City’s service area, demographics,
multi-source water supply, treatment, and conveyance/distribution facilities. The UWMP also
includes historical and future water demand to serve the buildout of the City consistent with the
General Plan which includes the Avila Ranch Project.
Since 1987, the City’s General Plan has included a Water and Wastewater Management
Element. The water section of the Element includes policies related to present water demand
and overall projected water demand. The Element also addresses water conservation, water
resource availability, accounting for siltation, multi-source water supply, and recycled water.
The LUCE update included a Water Supply Assessment for the areas within the City’s Urban
Reserve Line (URL). This WSA was for undeveloped and developed lands to be developed
pursuant to the LUCE.
4. WATER RESOURCE AVAILABILITY
As described in the Water Supply Section 2, the City has five water resources to meet current
and future City water demands: Salinas Reservoir (Santa Margarita Lake), Whale Rock
Reservoir, Nacimiento Reservoir, recycled water from the City’s Water Reclamation Facility, and
groundwater. In order to ensure water supply reliability, the City determined the amount of
water available from these water resources on an annual basis. The method to determine the
available yield from each resource varies based on water right, contractual agreement, or the
amount of water actually supplied.
For Salinas and Whale Rock Reservoirs the term “safe annual yield” is used to define the
annual amount of water available from these two resources. The two reservoirs are operated in
a coordinated manner to increase the available water. In contrast, the “dependable yield” from
Nacimiento Reservoir is the contractual amount of water to which the City has rights. Since
Nacimiento Reservoir is operated as a water supply project for Monterey County, the concept of
safe annual yield is not used for the City’s contractual water supply from this source. For
recycled water, the annual amount delivered is counted in the water availability calculation.
Though groundwater is part of the City’s water portfolio, due to the limitations on its use, the City
will not consider this supply in estimating available water resources to meet community needs.
Another issue is the potential impact of climate change on the City’s water resources. Climate
change could have a significant impact on future water availability in the form of droughts or
increased siltation in the reservoirs as a result of wildland fires which could affect the safe
annual yield of the City’s reservoirs. The City is currently experiencing its fourth consecutive
year of drought conditions, yet has been able to maintain a 36.5% reserve (reliability reserve
plus secondary water supply divided by primary water supply) above and beyond the amount
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needed for full buildout for more severe or unforeseen circumstances. The City continues
research on this topic and will monitor the potential for long-term impacts to its water supply
resources.
Tables 4-1 and 4-2 are summaries of the City’s available water resources.
Table 4-1. City Potable Water Resource Availability
Water Resource 2014 Annual Availability
Salinas Reservoir and Whale
Rock Reservoir
6,940 AF Safe Annual Yield
Nacimiento Reservoir 3,380 AF Contractual Limit
Siltation to 2060 (500 AF) Policy A 4.2.2
TOTAL 9,820 AF
Source: City of San Luis Obispo Water Resources Status Report, 2015
Note: Potable water supplies and recycled water supplies are separated for the purpose of this evaluation since
recycled water supplies cannot be used for some irrigation and domestic water purposes.
Table 4-2. City Non-Potable Water Resource Availability
Water Resource 2014 Annual Availability
Water Reclamation Facility 5,700 AF 2010 UWMP Section 5.2
Discharge to San Luis Obispo Creek (1,807 AF) 2010 UWMP Section 5.2
Recycled Water Use (185 AF) 2015 Water Resource Status Report
Recycled Water Distribution Capacity 1,000 AF 2008 OASP WSA
TOTAL 815 AF
5. WATER SUPPLY RELIABILITY
The water supply and reliability analysis provided by the 2010 UWMP uses historical information
since 1941 for evaluation of water supply availability and safe annual yield for the Salinas and
Whale Rock Reservoirs. The analysis of water supply availability is based on the controlled
drought period of the two reservoirs, which occurred between 1987 and 1991. Table 5-1 below
summarizes the results of that analysis and indicates the City’s water resources are reliable
during extended drought periods. Through the coordinated operation of Salinas and Whale
Rock Reservoirs and the ability to use other available water supplies (Nacimiento, recycled
water, and limited groundwater), climatic conditions such as prolonged drought do not impact
the City’s water supply.
As required by Section 5 of the City’s Water and Wastewater Element, the City will account for
water supplies necessary to meet three specific community needs, including primary water
supply, secondary water supply, and reliability reserve, see Table 5-2. The primary water
supply is defined as the amount of water needed to serve the build-out population of the city as
identified in the Land Use Element of the General Plan. The quantity of water needed for the
primary water supply is calculated using the ten-year average of actual per capita water use and
the city’s build-out population. The ten year average per capita water use (2006-2015) is 114.4
gallons per capita per day (gpcd). The proposed LUCE build-out population is estimated to be
57,200, and the Primary Water Supply is estimated to be 7,330 AF in the 2015 Water Status
Report.
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The reliability reserve provides a buffer for future unforeseen or unpredicted long-term impacts
to the City’s available water supply. The quantity of water for the reliability reserve is
established using twenty percent of the ten-year average of current per capita water use and the
City’s current population (45,802 in 2015). The reliability reserve provides as reserve above
and beyond the existing needs of the community and may not be used for future development.
It is currently estimated to be 1,174 AF.
The secondary water supply is the amount of water remaining from the City’s available water
resources above those needed to meet the primary water supply and reliability reserve. The
secondary supply identified to meet peak water demand periods or short-term loss of City water
supply sources. If combined with the reliability reserve, the secondary water supply provides an
estimate of the contracted or available water supply above and beyond that necessary to
support the buildout of the community.
Table 5-1. Water Supply Reliability
Average/Normal
Water Year (acre feet)
Single Dry Water
Year (acre feet) Year 1
Multiple Dry Water Years
Year 4 Year 2 Year 3
10,471 (1) 9,820 9,820 9,820 9,820 9,820
Percent of
Average/Normal Year 100% 100% 100% 100% 100%
Source: 2010 Urban Water Management Plan
Table 5-2. 2015 City Potable Water Supply Availability
Total 2015 Actual
Usage Primary Water Supply Reliability
Reserve
Secondary Water
Supply
9,820 4,990 7,330 1,174 1,316
6. WATER USAGE
Water use in the city includes single-family, multi-family, commercial (including institutional and
industrial), and irrigation customers. No agricultural uses are supplied by City water and the
City does not sell water to other agencies. The City does not have additional water demands
such as water use for saline barriers, groundwater recharge, etc. In 2014, the total water
demand for the city was 5,524 AF, and total demand in 2015 was 4,990 AF. The total water
demand is consistent with nationwide trends, due in part to conservation success and recent
recessionary impacts (vacancy rates, etc).
In 2008, a Water Supply Assessment (WSA) was completed on the Orcutt Area Specific Plan
(OASP) by the City. In this WSA, the projected water demand for the Orcutt Area was
calculated using the following water use factors for each land use category.
Single-family residences (R-1) 0.3 AF/year/unit
Single Family (R-2) 0.21 AF/year/unit
Apartment (R-3/R-4) 0.18 AF/year/unit
Neighborhood Commercial 0.3 AF/year/1,000 SF
Parkland 2 AF/year/acre
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6.1 Water Conservation Program:
Water conservation was first referenced as a part of the City's water management policy in
1973. In 1985, the City adopted the Annual Water Operational Plan policy, establishing 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. Experience from the drought of 1986 to
1991, the City developed a Water Shortage Contingency Plan to deal with immediate, short
term water shortages. The Plan is designed to require mandatory actions when there is a
projected three year supply of water remaining from available water resources. The Plan uses a
combination of water allocations based on customer classification and water use surcharges for
exceeding the allocation as a means to decrease water use during critical water shortages. For
instance, residential customers are given a water allocation based on the average water use for
multi or single family households having three occupants. If there are more residents,
additional water may be allocated with sufficient proof. Commercial customers are allocated
water either by a reduction based on their historical water use or by the average water use by
business type. Surcharges for exceeding a water allocation results in their bill either doubling or
tripling depending on the actual amount of water used. The Plan is also a required component
of the City’s UWMP which is updated every five years per State Water Code. The City also
recognizes the importance of long term water efficiency by supporting programs that will
enhance water supply reliability and comply with any current and/or future state mandates in
water use reductions. In 2009, Senate Bill X7 7 was passed requiring water agencies to reduce
per capita water use by 25 percent by the year 2020. The City’s target per capita water use
would be 117 gpcd. In 2013, the City already met that target with a use of 116 gpcd. In 2014,
the City’s use was estimated to be 95.8 gpcd. In terms of water supply reliability the City was
one of the original signatories to the Memorandum of Understanding (MOU) Regarding Urban
Water Conservation and has actively pursued the implementation of the water efficiency best
management practices (BMPs) prescribed in the MOU. The MOU was a negotiated agreement
between water purveyors statewide and environmental organizations on how best to utilize the
State’s water resources by incorporating conservation into their water management practices.
The BMPs have been developed over the years by water purveyors, environmental groups, and
industry stakeholders. They represent the best available water conservation practices based on
research and experience and include:
• Water conservation pricing and rate structures,
• Technical assistance for water customers,
• Incentives for indoor and outdoor water saving technologies,
• Public information and outreach, and
• Water audits.
On July 15, 2014, the California State Water Resources Control Board adopted emergency
drought regulations that were to be implemented by all urban water suppliers who have over
3,000 water connections regardless of that community’s water supply situation. Water
purveyors who do not implement the mandatory requirements face up to $10,000 per day in
fines and other penalties. The Emergency Regulations are in effect for 270 days but can be
rescinded, extended or amended based on drought conditions.
Notwithstanding the city’s stable water supply position, the Emergency Regulations specifically
mandate that the City implement mandatory outdoor water restrictions and water waste
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prohibitions or face fines up to $10,000 a day and no access to state grants and loans.
Accordingly, city council adopted an ordinance limiting the outdoor irrigation of ornamental
landscape and turf with potable water to three days a week, and allocated funding for education
and public outreach effects.
In response to the continued drought conditions, the State Water Board extended the 2014
emergency regulations and added new measures on March 17, 2015. As a result of these new
measures, the City is required to reduce its water use by an average of 12 percent from June
2015 to February 2016. To achieve this reduction, the City Council adopted a drought response
strategy in June 2015. This strategy includes:
• Adoption of a resolution declaring a drought emergency.
• Adoption of a resolution to defer new landscape installation or the use of modified
landscape plans during the drought emergency.
• Introduction of an ordinance amending Chapter 13.07 of the City’s Municipal Code to
include two-day-a-week and time-of-day restrictions for outdoor watering.
• Approval of an incentive program for high efficiency toilets and washing machines.
• Adoption of a resolution establishing a permit fee for the use of the Corporation Yard
groundwater well.
7. ENTITLEMENTS/REGULATORY APPROVALS
Water Code Section 10910(d)(2) requires the identification of existing water supply entitlements,
water rights, or water service contracts, federal, state, and local permits for construction of
necessary infrastructure, and any regulatory approvals required in order to be able to deliver the
water supply. The City's entitlements are described above in the section describing water
supply.
8. AVILA RANCH PROJECT
The Avila Ranch site will be developed into single-family and multi-family dwelling units,
commercial, parks, and open space. Table 8-1 shows a summary of the project water demands
under each land use area of the proposed site. These demands were calculated and presented
in the Preliminary Irrigation Water-Use Estimate, see Appendix A. The estimated total water
demand for the Avila Ranch Project is shown in Table 8-1.
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Table 8-1. Avila Ranch Water Demand – Project Specific
AREAS
Person
Per
Unit
Irrigation
Demand
potable
Irrigation
demand
non-potable
Indoor
Domestic
Demand
Total
R-1 2.29 1,631,774 3,155,243 4,787,017
R-2 2.29 2,674,323 8,435,634 11,109,957
R-3 2.29 530,809 4,578,195 5,109,004
R-4 2.29 457,790 3,093,375 3,551,165
Commercial 144,412 144,412
Community
Garden Beds 247,387 247,387
Riparian Open
Space 3,518,296 3,518,296
Drought Tolerant
Open Space 4,333,923 4,333,923
Turf (Park Area) 8,285,718 8,285,718
Bioretention Areas 864,905 864,905
Drought Tolerant
Parkways 654,387 654,387
Total
(gallons/year): 4,306,097 19,037,627 19,262,446 42,606,170
Total (acre-
feet/year): 13 59 59 131
For comparison, Table 8-2 was developed to project Avila Ranch’s water demand using the
same water use factors that were used in the 2008 OASP WSA. These factors reflect water
use factors from 2008 and before that, by current standards are approximately 30 percent
higher than the water usage reported in 2015. Since that time the City and state have
implemented water conservation measures for indoor and outdoor water usage. Nevertheless,
these factors provide a useful comparison of the project’s projected water usage to that of the
most recent City specific plan, and provide an additional level of caution in making a
determination of the adequacy of water supplies. Using these water demand factors shows
that the total water use of Avila Ranch would potentially be 187.85 AF/year. This is higher than
the estimated total water demand that has been calculated for the development.
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Table 8-2. Avila Ranch Project Water Demand by Use Factors
AREAS Water Use
Factor
Quantity Water Demand
Single-Family Residences
(R-1)
0.3 AF/year/unit 105 31.5
Single Family (R-2) 0.21 AF/year/unit 305 64.05
Apartment (R-3/R-4) 0.18 AF/year/unit 310 55.8
Neighborhood Commercial
0.3
AF/year/1,000
SF
15,000 4.5
Parkland 2 AF/year/acre 16 32
Total (acre-feet/year): 187.85
Note: R-1 zoning = Single-family residence
R-2 zoning = Single family
R-3 & R-4 zoning = Apartments
Table 8-3 compares the City’s available water with Avila’s projected usage. Avila Ranch’s
potable water use is well within the limits of available water supply.
Table 8-3. City Water Supply Availability and Avila Ranch Water Usage
City Water
Supply
City
Water
Usage
City Water
Available
Avila Ranch Use
(project
specific)
Avila Ranch Use
(calculated by
use factors)
Potable Water 9,820 4,990 4,830 72 155.85
Recycled
Water 1,000 185 815 59 32
As shown in Table 8-1 above, 59 AF/year is planned to come from non-potable sources with the
release of recycled water lines to the site. Appendix B shows the recycled water use area’s
within Avila Ranch. Recycled water from the City is an obvious first choice and the City has
projected 1,000 AF/year of available supply. The project also has an existing well that is located
on the north-west corner of the site. The well is currently being tested for water quality, as well
as production capabilities. If production rates are high enough, this well could potentially be
used for non-potable water at the proposed parks. This could result in a potential reduction in
the overall demand from the City by up to 59 AF/year.
Potential water-saving programs will be implemented for the project in an attempt to reduce the
water demand use even further as part of the Water Conservation Policy 7.2.2 in the Airport
Area Specific Plan, see Appendix C. This involves using reclaimed water for all planter areas
except the residential lots, water saving devices and features in the design of the homes and
lots, and potential for using the existing onsite well for onsite irrigation. All plant species
selected for the parkways, and drought tolerant open space areas of the site meet the Very Low
Water Needs categories under the California Water Use Classification of Landscape Species
(WUCOLS) list. All of the planter areas except the turf play areas and portions of the community
garden beds are intended to be irrigated using drip and/or low-volume irrigation equipment. In
addition, it is anticipated that the native plantings in the drought tolerant and riparian open space
areas will receive temporary establishment irrigation that will be reduced over time and
eventually activated only during periods of extended drought or prolonged periods of high
temperatures.
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The irrigation design shall implement all appropriate and available tools and techniques towards
achieving maximum water application uniformity (distribution uniformity). Such measures will
include utilizing dedicated landscape water meters, soil moisture sensors, central irrigation
controllers and master valves combined with flow sensors. Weather based irrigation controllers
that are tied to CIMIS (California Irrigation Management Information System) weather data will
be used for the larger landscape areas. This type of controller communicates with a nearby
CIMIS weather station and adjusts irrigation application based on real-time weather conditions.
Other smaller landscape areas or POC’s (Points of Connection) may utilize basic weather
based ‘smart’ irrigation controllers, that adjust water application based on historic Eto data pre-
programed into the controller, as opposed to actual real-time weather data.
Irrigation zones will be determined by means of defining hydrozones, whereby all irrigation
circuits will be spatially defined by virtue of grouping plants with the same water needs and
similar climatic and soil conditions (and/or other factors that impact watering needs).
Per appendix A, all planter areas, except Turf (Park Areas) are using ETAF (Evapotranspiration
adjustment factor) of 0.50.
9. CONCLUSION
The water supply demand for the Avila Ranch project was included in the City’s Land Use and
Circulation Element Update Water Supply Assessment. A sufficient water supply is available to
serve the project no matter which method is used to calculate the demand.
Using project-specific water demand information, 72 AF/year of the City’s 4,830 AF/year of
available supply is required (1.5% of available supply), and 59 AF/year of the 815 AF/year of
available recycled water (7.2%) would be utilized. Both of these water needs are within the
water demand calculated as part of the primary water supply.
Using land use water factors from the OASP WSA gives a total water demand of 187.85
AF/year. 155.85 AF/year of the City’s 4,830 AF/year of available supply is required (3.2% of
available supply), and 32 AF/year of the 815 AF/year of available recycled water (3.9%) would
be utilized. These estimates are for comparison purposes and are based on 2008 water use
factors in the community. Per capita water use in the community has declined substantially in
the community since that time, both as a result of voluntary conservation efforts, changes in
building code requirements, and state-mandated reductions in water usage. Nevertheless,
based on these water use statistics, there is a sufficient supply of water to meet the project’s
needs.
This conclusion was determined based on this Water Supply Assessment and supporting
information in the records of the City of San Luis Obispo.
Avila Ranch WSA
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12/17/2015 12
REFERENCES
San Luis Obispo, City of. General Plan – Chapter 8 Water and Wastewater Management Element.
Adopted February 24, 1987, Revised May 2015
San Luis Obispo, City of. 2010 Urban Water Management Plan. Adopted June 21, 2011
San Luis Obispo, City of. Land Use and Circulation Element Update Water Supply Assessment. Adopted
June 2014
San Luis Obispo, City of. Orcutt Area Specific Plan – Water Supply Assessment. Approved March 5, 2008
San Luis Obispo, City of. 2015 Water Resources Status Report
Memorandum of Understanding Regarding Urban Water Conservation in California. Amended September
17, 2014
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TECHNICAL APPENDICES
The following technical appendices are included:
• Appendix A: Preliminary Irrigation Water-Use Estimate
• Appendix B: Avila Ranch Recycled Water Use Areas
• Appendix C: Airport Area Specific Plan: Water Conservation Policy 7.2.2
APPENDIX A: PRELIMINARY IRRIGATION WATER-USE ESTIMATE
AVILA RANCH Preliminary Irrigation Water‐Use Estimate9/15/2015 NOTES:SUMMARY OF ESTIMATED WATER USE (Refer to Detailed Preliminary Calculations on the following page) MAWA (Gallons)PRE‐EMERGENCY REGULATIONSAREASHYDROZONES (SF) MAWA (Gallons)ETWU (Gallons) ETAF Used43.8 x 0.62 x ([0.7 x LA) / (0.3 x SLA) RIPARIAN OPEN SPACE284,437 3,947,417 3,518,2960.5 5,492,251DROUGHT TOLERANT OPEN SPACE463,422 6,431,371 4,333,9230.5 8,948,308TURF (at Parks) ‐ Hybrid Bermuda328,586 8,923,081 8,285,7181.0 6,344,733COMMUNITY GARDEN BEDS20,000 277,560 247,3870.5 386,184BIORETENTION AREAS72,448 1,005,433 864,9050.5 1,398,913DROUGHT TOLERANT PARKWAYS52,904 734,202 654,3870.5 1,021,534COMMERCIAL (10% of Total SF)11,675 162,026 144,4120.5 225,435R‐3 RESIDENTIAL (20% of Total SF)43,980 597,160 530,8090.5 849,219R‐4 RESIDENTIAL (20% of Total SF)37,930 515,014 457,7900.5 732,398R‐2 / 4‐PACK RESIDENTIAL98,280 1,334,446 1,186,1740.5 1,868,224R‐2 / 6‐PACK RESIDENTIAL123,300 1,674,167 1,488,1490.5 2,343,834R‐1 / SINGLE FAMILY RESIDENTIAL135,200 1,835,746 1,631,7740.5 2,570,044TOTAL IRRIGATED LANDSCAPE2,088,347 27,437,622 23,343,72432,181,076TOTAL IRRIGATED LANDSCAPE IN ACRES: 47.9‐14.74%ACRE FEET WATER: 84.20 71.64 MAWA ‐ Maximum Applied Water Allowance ETWU ‐ Estimated Total Water UseNote: All planter areas except Turf at Parks are using ETAF of 0.50The following landscape irrigation calculations are based on the current TTM and preliminary site plans to date. This Preliminary Irrigation Water‐Use Estimate is only considered an approximation of the final landscape irrigation needs and is based on City of SLO Resolution: R‐10628 and direction provided by Ron Munns. Irrigation calculations may change as the project progresses, and calculations are subject to revisions as required on subsequent submittals. Actual water use may be lower than as indicated in these calculations since planting density is likely to be less than average in the Native Riparian and Native Open Space categories. ETo Rate of 43.80 used (Per California Dept. of Water Resources. The Agricultural Parcel and Orchard areas are not included in these calculations. PERCENTAGE DIFFERENCE IN RELATION OF CURRENT MAWA TO PRE‐EMERGENCY MAWAAvila Ranch VTM ‐ Preliminary Landscape Water Calculations Sep. 15, 2015
AVILA RANCH Preliminary Irrigation Water‐Use Estimate9/15/2015PROPOSED LAND USETOTAL LANDSCAPE AREA (SF)WATER USE PER (WUCOLS)PLANT FACTOR (WUCOLS)REFERENCE EtoEto ADJUSTMENT FACTORESTIMATED HYDROZONE (SF)IRRIGATION EFFICIENCYMAWA (Gal/Yr.)ETWU (Gal/Yr.)POTABLE OR RECLAIMED WATER NOTESRIPARIAN OPEN SPACE 296,266 MODERATE 0.4 43.8 0.5 284,437 0.9 3,947,417 3,518,296 ReclaimedSLA included in calculationDROUGHT TOLERANT OPEN SPACE 814,865 LOW 0.3 43.8 0.5 463,422 0.9 6,431,371 4,333,923 ReclaimedSLA included in calculationTURF (at Parks) ‐ Hybrid Bermuda 379,900 HIGH 0.65 43.8 1.0 328,586 0.7 8,923,081 8,285,718 ReclaimedETAF of 1.0 used as directed by Ron Munns of City of SLOCOMMUNITY GARDEN BEDS 20,000 MODERATE 0.4 43.8 0.5 20,000 0.9 277,560 247,387 PotableSLA included in calculationBIORETENTION AREAS 74,047 LOW 0.3 43.8 0.5 72,448 0.7 1,005,433 864,905 ReclaimedSLA included in calculationDROUGHT TOLERANT PARKWAYS 52,904 LOW 0.4 43.8 0.5 52,904 0.9 734,202 654,387 ReclaimedSLA included in calculationCOMMERCIAL (10% of Total SF) 11,675 LOW 0.4 43.8 0.5 11,675 0.9 162,026 144,412 ReclaimedSLA included in calculationR‐3 RESIDENTIAL (20% of Total SF) 43,980 LOW 0.4 43.8 0.5 43,980 0.9 597,160 530,809 ReclaimedETAF of 0.5 used as directed by Ron Munns of City of SLOR‐4 RESIDENTIAL (20% of Total SF) 37,930 LOW 0.4 43.8 0.5 37,930 0.9 515,014 457,790 ReclaimedETAF of 0.5 used as directed by Ron Munns of City of SLOR‐2 / 4‐PACK RESIDENTIAL 98,280 LOW 0.4 43.8 0.5 98,280 0.9 1,334,446 1,186,174 PotableETAF of 0.5 used as directed by Ron Munns of City of SLOR‐2 / 6‐PACK RESIDENTIAL 123,300 LOW 0.4 43.8 0.5 123,300 0.9 1,674,167 1,488,149 PotableETAF of 0.5 used as directed by Ron Munns of City of SLOR‐1 / SINGLE FAMILY RESIDENTIAL 135,200 LOW 0.4 43.8 0.5 135,200 0.9 1,835,746 1,631,774 PotableETAF of 0.5 used as directed by Ron Munns of City of SLOTOTAL PROJECT : 2,088,34727,437,622 23,343,724IRRIGATION DESIGN APPROACH:ALL PLANTER AREAS (EXCEPT THE LAWN & BIO‐RETENTION AREAS) ARE INTENDED TO BE IRRIGATED USING DRIP AND/OR LOW‐VOLUME IRRIGATION EQUIPMENT.LAWN PLANTERS WILL LIKELY BE IRRIGATED WITH ROTOR OR ROTARY SPRAY POP‐UP NOZZLES. BIORETENTION AREAS WILL BE IRRIGATED WITH ROTOR OR ROTARY SPRAY POP‐UP NOZZLES, DUE TO POSSIBLE SOIL MAINTENANCE DAMAGE TO A DRIP SYSTEM.SMALL LAWN AREAS MAY BE IRRIGATED WITH SUB‐SURFACE, IN‐LINE DRIP EMITTERS WITH AIR RELIEF AND FLUSH VALVES.RECLAIMED WATER WILL BE UTILIZED FOR ALL PLANTER AREAS, WITH THE EXCEPTION OF THE RESIDENTIAL LOTS.WEATHER BASED IRRIGATION CONTROLLERS WILL BE UTILIZED AND WILL INCLUDE A WEATHER SENSOR OVERRIDE DEVICE. ALL SYSTEMS WILL INCLUDE (1) MASTER VALVE AND FLOW SENSOR AT EACH POINT OF CONNECTION. ALL TREES THAT ARE NOT LOCATED AMONG SHRUB BEDS AREAS SHALL RECEIVE DEEP ROOT BUBBLER IRRIGATION. AN PLANT ESTABLISHMENT IRRIGATION SCHEDULE (FIRST 6 MONTHS) AND A POST‐ESTABLISHMENT IRRIGATION SCHEDULE WILL BE PROVIDED WITH CONSTRUCTION DRAWINGS.Avila Ranch VTM ‐ Preliminary Landscape Water Calculations Sep. 15, 2015
APPENDIX B: AVILA RANCH RECYCLED WATER USE AREAS
APPENDIX C: AIRPORT AREA SPECIFIC PLAN: WATER CONSERVATION POLICY 7.2.2