HomeMy WebLinkAboutR-11616 adopting amendments to the Water and Wastewater Element of the General Plan (GENP-0762-2025)R 11616
RESOLUTION NO. 11616 (2025 SERIES)
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF SAN LUIS
OBISPO, CALIFORNIA, ADOPTING AMENDMENTS TO THE WATER
AND WASTEWATER ELEMENT OF THE GENERAL PLAN (GENP-0762-
2025)
WHEREAS, Government Code Section 65300 mandates all cities and counties to
adopt a comprehensive, long-term general plan to guide their physical development; and
WHEREAS, the Water and Wastewater Element of the City of San Luis Obispo
General Plan was last updated in 2020 in compliance with State law; and
WHEREAS, General Plan Water and Wastewater Element Policies state that the
City’s wastewater collection system shall support population and related service demands
consistent with the General Plan (Policy B 2.2.2), and the City shall collect and convey all
wastewater under safe and sanitary conditions to the Water Resource Recovery Facility
(Goad B 4.1), and maintain, and revise as necessary, master plans for the extension of
wastewater services to developing areas of the City and to ensure orderly replacement
of aged infrastructure (Program B 4.3.5); and
WHEREAS, the City of San Luis Obispo has prepared amendments to the General
Plan Water and Wastewater Element to incorporate current information including an
updated wastewater collections system capacity-constrained area map and associated
references to current wastewater flow and infrastructure studies (2025 Wastewater
Collections Infrastructure Renewal Strategy), and minor text edits to provide currently
available information regarding the wastewater collections system and Water Resource
Recovery Facility (Exhibit A); and
WHEREAS, the Planning Commission, at the hearing of October 22, 2025,
considered the proposed amendments to the General Plan Water and Wastewater
Element, found the proposed amendments consistent with the General Plan, and
recommended the City Council approve amendments to the General Plan Water and
Wastewater Element and proposed categorical exemptions to the California
Environmental Quality Act; and
WHEREAS, the City Council, at the hearing of December 2, 2025, considered
amendments to the General Plan Water and Wastewater Element and proposed
categorical exemptions to the California Environmental Quality Act.
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Resolution No. 11616 (2025 Series) Page 2
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NOW, THEREFORE, BE IT RESOLVED by the Council of the City of San Luis
Obispo as follows:
SECTION 1. Findings. The City Council, after considering the proposed
amendments to the Water and Wastewater Element, staff presentation and
recommendation, public testimony and correspondence, and reports thereon, and the
Planning Commission’s recommendation to find the amendments consistent with the
General Plan and find the action categorically exempt from the California Environmental
Quality Act, make the following findings:
a) The proposed amendments to the Water and Wastewater Element are
consistent with the General Plan.
b) The amendments to the Water and Wastewater Element are exempt from the
California Environmental Quality Act (CEQA) pursuant to CEQA Guidelines
Sections 15307 (Actions by Regulatory Agencies for Protection of Natural
Resources) and 15308 (Actions by Regulatory Agencies for the Protection of
the Environment) because the intent of the capacity-constrained area map is
to identify these areas in the City’s general plan such that land use planning
can occur with these capacity limitations in mind. In addition, the updated map
and policies to remain provide a basis in the General Plan for programs that
reduce I&I and the potential for SSOs. Implementation of programs that
address these capacity-related issues would have a beneficial impact on the
environment by reducing the potential for I&I and overflows due to reduced
flows from groundwater and stormwater.
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Resolution No. 11616 (2025 Series) Page 3
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SECTION 2. City Council Action. The City Council, after considering the proposed
amendments to the Water and Wastewater Element, staff presentation and
recommendation, public testimony and correspondence, and reports thereon, and the
Planning Commission’s recommendation, approve adoption of the General Plan Water
and Wastewater Element (Exhibit A).
Upon motion of Vice Mayor Shoresman, seconded by Mayor Stewart, and on the
following roll call vote:
AYES: Council Member Boswell, Francis, Vice Mayor Shoresman, and
Mayor Stewart
NOES: None
ABSENT: Council Member Marx
The foregoing resolution was adopted this 2nd day of December 2025.
___________________________
Mayor Erica A. Stewart
ATTEST:
______________________
Teresa Purrington
City Clerk
APPROVED AS TO FORM:
______________________
J. Christine Dietrick
City Attorney
IN WITNESS WHEREOF, I have hereunto set my hand and affixed the official seal of the
City of San Luis Obispo, California, on ______________________.
___________________________
Teresa Purrington
City Clerk
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EXHIBIT A – WATER AND WASTEWATER ELEMENT PROPOSED AMENDMENTS
LEGISLATIVE DRAFT
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Water and Wastewater Element
WASTEWATER SERVICE
B 2.0 Background
The City is the sole provider of wastewater service within the City. The service provides collection and treatment
for residential, commercial, and industrial users on properties within the city limits. In 20182025, the number of
service connections is estimated to be 12,00013,421. Through agreement, the City also provides service to the
San Luis Obispo campus of California Polytechnic State University (Cal Poly) and the County of San Luis Obispo
Airport.
The collection system is primarily a gravity flow system. Where gravity flow is not feasible due to the topography,
wastewater lift stations and pressurized force mains are used to move wastewater to the City’s Water Resource
Recovery Facility on Prado Road. Sewer pipelines measure from six inches to 48 inches in diameter.
The City completed a two-year Flow Monitoring and Inflow/Infiltration Study in 2012. Using data from this
Study, pipeline condition data from its asset management database, and growth assumption from the General
Plan’s Land Use (2014) and Housing (2015) elements, the City completed hydraulic modeling and its
Wastewater Collection System Infrastructure Renewal Strategy in 2016. The Renewal Strategy identified a
prioritized list of capital projects to address the City’s aging infrastructure. The Renewal Strategy also
identified capacity constrained areas during wet weather events due to inflow and infiltration, shown in Figure
3. Inflow and infiltration is discussed further in section B.4.0.
The City completed an updated Wastewater Collection System Infrastructure Renewal Strategy (WWCIRS) in
July 2025. Development of the 2025 WWCIRS included the collection of wastewater flow data, the completion
of a system-wide capacity modeling study in 2024, the incorporation of growth estimates based on build-out
of the City’s General Plan and underlying zoning for each parcel, including assumptions for accessory dwelling
units and developments that include a density bonus, and the completion of an updated wastewater flow
model. Based on the results of the analysis, recommendations for capital improvement sewer projects are
included in the 2025 WWCIRS. The WWCIRS also identified updated capacity-constrained areas during wet
weather events due to inflow and infiltration. The updated capacity-constrained area map is included in this
Element as Figure 3. Inflow and infiltration, and is discussed further in section B.4.0.
Following completion of a major upgrade in 2025 to increase capacity to serve the City’s build-out population
outlined in the Land Use Element, Tthe Water Resource Recovery Facility (WRRF) is designed for an average dry-
weather flow of 5.1 5.4 million gallons per day (mgd). Instantaneous peak flows exceeding 20 mgd are not
uncommon during storm events due to infiltration and inflow into the wastewater collection system, discussed
further in subsection B 4.0. As the City grows to its build-out population outlined in the Land Use Element, the
average dry-weather flow of wastewater is expected to reach 5.4 mgd. In 2018, design for the expansion of the
Water Resource Recovery Facility to accommodate General Plan buildout is underway. When the WRRF is
expanded in the future it will have a treatment capacity of 5.4 mgd.
B 2.1 Goal
Adequate wastewater collection and treatment service to meet the long-term needs of the City.
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B 2.2 Policies
B 2.2.1 Service Outside the City Limits
To receive City wastewater service, property must be annexed to the City. The City Council may authorize
exceptions to this policy provided it is found to be consistent with the General Plan.
B 2.2.2 Service Capacity
The City's wastewater collection system and Water Resource Recovery Facility shall support
population and related service demands consistent with the General Plan.
B 2.2.3 Wastewater Service for New Development
New development shall pay its proportionate or “fair share” of expanded treatment and collection
system capacity and upgrades. New development will only be permitted if adequate capacity is available
within the wastewater collection system and/or Water Resource Recovery Facility.
B 2.2.4 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).
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Figure 3 Capacity Constrained Areas [delete and replace]
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Figure 3 Capacity Constrained Areas
B 2.3 Programs
B 2.3.1 Expand capacity in the City’s collection system and Water Resource Recovery Facility in support of
projected wastewater flows.
B 2.3.2 Evaluate the potential for the wastewater flows of a proposed project to exceed the capacity of
collection and treatment systems.
B 2.3.3 The City will conduct periodic updates to its wastewater development impact fees.
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WASTEWATER TREATMENT
B 3.0 Background
The Water Resource Recovery Facility processes wastewater in accordance with standards set by the State's
Regional Water Quality Control Board (RWQCB). The RWQCB issues a permit to the City under the National
Pollutant Discharge Elimination System (NPDES), setting standards for the discharge of treated wastewater. The
standards are to protect beneficial uses of the receiving water (San Luis Obispo Creek), including recreation,
agricultural supply, and fish and wildlife habitat.
The Water Resource Recovery Facility removes solids, reduces the amount of nutrients, and eliminates bacteria in
the treated wastewater, which is then discharged into San Luis Obispo Creek. Solids are separated and treated to
create biosolids. Biosolids are beneficially reused as compost and/or soil amendment. As described in Section A
7.0, the Water Resource Recovery Facility has been producing tertiary-treated recycled water for delivery to
water customers in the City since 2006.
The design phase for theA comprehensive upgrade of the Water Resource Recovery Facility is underway with
completion of construction anticipated in 2022was completed in 2025. The upgrade increased average daily dry
weather capacity at the facility to 5.4 mgd, and included, but was not limited to, expansion of an equalization basin
that provides additional flood protection measures and operational flexibility, and construction of a new membrane
and ultra-violet disinfection (MBR-UV) facility. The upgrade will also enable the City to consider potable reuse, part
of a One Water concept, in the future.
B 3.1 Goals
B 3.1.1 Wastewater treatment that meets or exceeds regulatory requirements and ensures the protection of public
health and the environment.
B 3.1.2 Maximize recycled water production.
B 3.2 Policies
B 3.2.1 Treating Wastewater
The City will treat all wastewater in compliance with approved discharge permits.
B 3.2.2 Recycled Water Production
The City will produce high-quality, dependable recycled water, suitable for a wide range of uses.
B 3.2.3 Beneficial Use
The City will pursue treatment and disposal methods which provide for further beneficial use of wastewater
and biosolids.
B 3.3 Programs
B 3.3.1 Prepare and implement Water Resource Recovery Facility master plan consistent with regulatory
requirements.
B 3.3.2 Work cooperatively on regional water quality issues.
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COLLECTION SYSTEM
B 4.0 Background
The first sanitary sewers were built in San Luis Obispo in the late 1800s. Today, portions of the collection system
are over 100 years old. It includes nine lift stations, approximately 1385 miles of gravity sewer line, and three
miles of force main. Approximately 2,9003,184 manholes provide access to the collection system. The sewer
lines are made of a variety of materials, including ductile iron pipe, terra cotta salt-glazed pipe, vitrified clay pipe
(VCP), polyvinyl chloride (PVC), high-density polyethylene (HDPE) and asbestos concrete.
The City’s wastewater collection system requires maintenance to ensure uninterrupted flows and minimize
sanitary sewer overflows. Area and preventive maintenance programs are regularly evaluated to ensure their
effectiveness. The City also utilizes video inspection to prioritize problem areas for replacement, maintenance,
assess overall mainline conditions, conduct inflow and infiltration evaluations, and assess new construction.
The City issues discharge permits to and conducts inspections of facilities that have the potential to discharge
pollutants in concentrations that could pose a threat to worker safety, the wastewater collection system, and/or
the Water Resource Recovery Facility. Through its Pretreatment Program, the City also implements programs to
target constituents of special concern.
Like most cities in California, San Luis Obispo has separate sewer and storm drain systems. This means each
system of pipes in the ground is designed to accommodate either sewer or stormwater flows. One set of pipes
takes sanitary waste to the Water Resource Recovery Facility while a second set carries stormwater runoff from
street drains directly into bioswales, detention basins, or creeks.
The City’s wastewater collection system and the Water Resource Recovery Facility have long experienced
problems associated with wet weather infiltration and inflow (I & I). Inflow is water that enters the collection
system at points of direct connection (non-soil) such as around manhole covers or through illegal connection of
roof drains, downspouts, or landscape drains. Infiltration is water that flows through the ground into the
collection system usually through cracks in public sewer mains and/or private sewer laterals (See Figure 4). I & I
overloads the collection system during heavy rains and can result in sanitary sewer overflows. During periods of
significant rain events, the Water Resource Recovery Facility can become hydraulically overwhelmed (as
mentioned previously, instantaneous peak flows exceeding 20 mgd are not uncommon during storm events),
increasing the chance of effluent violations and the release of partially treated wastewater to San Luis Obispo
Creek. Table 6 includes data on the highest average daily flows experienced at the Water Resource Recovery
Facility during rain events over a nine-19-year period.
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Water and Wastewater Element
Table 6. Highest Average Daily Flows to the Water Resource Recovery Facility, 2006 to
20172024
Average Daily Flows 1 Year
19.75 mgd 2006 (April)
7.24 mgd 2007(December)
9.83 mgd 2008 (January)
11.67 mgd 2009 (October)
13.51 mgd 2010 (December)
13.23 mgd 2011 (March
7.10 mgd 2012 (January)
5.17 mgd 2013 (January)
5.12 mgd 2014 (March)
5.24 mgd 2015 (February)
5.63 mgd 2016 (March)
9.00 mgd 2017 (February)
10.626 2018 (March)
10.19 2019 (March)
6.86 2020 (March)
11.18 2021 (January)
6.92 2022 (December)
172 2023 (January)
9.26 2024 (April)
Notes:
1. Instantaneous peak flows are higher.
August dry weather flow to the Water Resource Recovery Facility was 1.91 mgd in 2016 and 2.80 mgd in 2017.
Source: City of San Luis Obispo Utilities Department, 2018.
2. At the time of measurement, during the WRRF upgrade project, maximum measurement limit was 17 mgd.
Actual flows exceeded this amount.
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Figure 4 Inflow and Infiltration Illustrated
B 4.1 Goal
Collect and convey all wastewater under safe and sanitary conditions to the Water Resource Recovery Facility.
B 4.2 Policies
B 4.2.1 Collection System Maintenance
The City will manage the collection system to ensure that the proper level of maintenance is provided and that the
flow in sanitary sewers does not exceed design capacity.
B 4.2.2 Infiltration and Inflow
The City will minimize stormwater and groundwater infiltration and inflow into the sewer system.
B 4.3 Programs
B 4.3.1 Investigate and carry out cost-effective methods for reducing infiltration and inflow into the wastewater
collection system.
B 4.3.2 Develop education and outreach materials to increase public awareness of problems associated with excessive
infiltration and inflow (I & I) into the wastewater collection system and the City’s efforts to reduce I & I.
B 4.3.3 Support the retrofit of commercial and residential sewer laterals to reduce infiltration and inflow into the
wastewater collection system.
B 4.3.4 Update the Sewer System Management Plan to maintain its applicability.
B 4.3.5 Maintain, and revise as necessary, master plans for the extension of wastewater services to developing areas of the
City and to ensure orderly replacement of aged infrastructure.
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B 4.3.6 Review development proposals to ensure new development does not adversely impact existing infrastructure and
that necessary infrastructure will be in place to support the development.
B 4.3.7 Provide a Pretreatment Program pursuant to the Clean Water Act to ensure that all discharge requirements are
met.
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