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City Of san pais oBispo December 14, 1993
COUNCIL AGENDA REPORT ITEM NUMBER:
FROM: JohnMossy% Prepared By: Gary W. Henderson 4• %A
Utilities D' ecto Water Division Manager
SUBJECT: Salinas Reservoir Expansion Project Draft Environmental Impact Report
CAO RECOMMENDATION
Receive this report regarding the findings of the Draft Environmental Impact Report for the
Salinas Reservoir Expansion Project
DISCUSSION
Background
The concept of expanding the Salinas Reservoir by installing spillway gates has been evaluated
in previous reports and determined to be a favorable project for increasing the available water
supplies for the City of San Luis Obispo. The proposed project would raise the maximum water
surface elevation at the reservoir by approximately 19 feet and expand the maximum storage
capacity from 23,843 acre feet (AF) to 41,792 AF, an approximate 75 percent increase in
capacity. The increased storage capacity would result in an increase of approximately 1,650
acre feet per year (AFY) of safe annual yield for the City.
The Salinas Dam and Reservoir were built in 1941 by the War Department (now the U.S. Army
Corps of Engineers) to supply water to Camp San Luis Obispo and the City of San Luis Obispo.
The Salinas Project (dam, pipelines, property, etc.) is owned by the Army Corps of Engineers
(ACOS) and is leased to the San Luis Obispo Flood Control and Water Conservation District
(SLOFCWCD) for its operation and maintenance. The water from the project is regulated under
water rights permits issued to the ACOS and the City of San Luis Obispo. The City is the only
user of water from the reservoir. The ACOS has indicated that the Salinas Reservoir Expansion
Project can not proceed until ownership of the property and facilities is transferred to a local
agency.
The preparation of the EIR for the proposed expansion project began in June of 1992 when the
Notice of Preparation was issued. The schedule for completion of the EIR and Council
certification was originally estimated to be December 1993. Two particular issues have come
up since beginning work on the EIR that have impacted the scheduled completion. The first
issue involved the need to develop a conceptual recreation facilities relocation plan which would
be acceptable to County Parks staff. This plan had to be prepared so that the impacts relative
to the relocations could be evaluated in the EIR. The second issue involves the necessity to
transfer the ownership of the facilities prior to project implementation. A number of meetings
with the ACOE were needed to determine the process and additional studies necessary to allow
for the transfer to occur.
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COUNCIL AGENDA REPORT
Salinas Reservoir Draft EIR
Page 2
Draft Environmental Impact Report
The draft environmental impact report (EIR) has been prepared for the City of San Luis Obispo,
as lead agency for compliance with the California Environmental Quality Act (CEQA), by
Woodward-Clyde Consultants of Santa Barbara. Woodward-Clyde also prepared earlier reports
concerning the geotechnical, seismic and dam safety, hydrology, and reservoir yield evaluations.
The draft EIR was released for public review on November 19, 1993, and the close of the public
comment period is set for January 3, 1994. The EIR addresses potential impacts associated with
the following major reservoir expansion project components:
■ Expansion of reservoir capacity and associated inundation of shoreline (approximately
400 acres) and effects on downstream flow regime
■ Spillway modification and strengthening of dam base
■ Relocation of recreation facilities and associated access roads that would be inundated in
the County Park
■ Maintenance of north-shore road segments that would be periodically inundated
Summary of Impact Findings
The primary impacts of potential concern associated with the proposed project are related to
inundation of shoreline areas and reductions in downstream flows. The reservoir currently
covers approximately 730 surface acres when full. Following project completion, an additional
400 acres of land will be periodically inundated (1,128 surface acres total). The proposed
project would also periodically reduce downstream flows during the wet winter months until the
reservoir filled to its expanded capacity. The reservoir facilities would continue to be operated
in compliance with the requirements of the "live stream agreement", thus minimizing impacts
to downstream water users. The following summary briefly outlines the major potential impacts
associated with the proposed project and potential mitigation measures to reduce or eliminate the
impacts.
1. Inundation of Oak Trees
Impact: The inundation of an additional 400 acres will result in the loss of an
estimated 4,000 oak trees and 930 grey pines.
Potential Mitigations: The approximate 4,000 oak trees that would be inundated, or
cleared during the recreational facilities/roadway relocation activities,
could be compensated, in part, by a direct replacement effort based on a
1:1 to 4:1 replacement ratio. The restoration effort could occur on land
surrounding the reservoir and/or at an appropriate offsite property.
Monitoring would be required for at least 3 to 5 years. The City may
LA'scity Of Sar. 11S OBISPO
WA COUNCIL AGENDA REPORT
Salinas Reservoir Draft EIR
Page 3
also consider providing funds for an offsite oak tree restoration project to
offset the impacts identified.
2. Inundation of Wetlands
Impact: The expanded reservoir storage capacity will result in the inundation of
about 89 acres of wetlands (freshwater marsh and streambank woodlands).
The majority of the wetlands occur at the back part of the lake where the
Salinas River and other tributary streams enter the lake. The majority of
the wetland areas to be inundated are expected to reform around the new
lake shore over time and may actually increase in acreage with respect to
current conditions. The inundation will potentially impact plants and
animals in the existing wetland areas.
Potential Mitigations: To mitigate the potential impact to red-legged frogs, a habitat
enhancement program is recommended for the upstream portions of Alamo
Creek. Barriers to upstream migration of predators could be installed.
Other measures recommended to mitigate impacts to vegetation include
monitoring of inundation effects on riparian vegetation and monitoring the
progress of the expected reestablishment of riparian woodlands at, and
adjacent to, the new reservoir level. Remedial measures may be
considered to reestablish riparian woodland habitat if natural
reestablishment does not begin to occur within several years.
3. Recreation Facilities
Impact: A large portion of the existing recreation facilities and related access roads
will be inundated following expansion of the reservoir capacity.
Recreation facilities which will have to be relocated as part of the
project include the marina building, cafe building, swimming pool and
related facilities, White Oak playground area, etc.
Mitigations: The proposed project includes extensive plans to mitigate effects on
recreational facilities and associated roadways in the County Park. In
general, all facilities impacted would be relocated or replaced. The
proposed relocation plans are designed to improve park facilities with
respect to parking, traffic circulation, and aesthetics. Relocation of these
facilities will result in short-term adverse effects on recreational
opportunities and use during the construction phase due to expected partial
park closures for public safety.
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'A-Me COUNCIL AGENDA REPORT
Salinas Reservoir Draft EIR
Page 4
4. Downstream Flow Reductions
Impact: The proposed project would periodically reduce downstream flows during
wet winter months until the reservoir filled to its expanded capacity.
Computer model simulations for estimated reductions in downstream flows
have been performed.to identify impacts associated with this project. The
average annual reduction, following project completion, relative to
historical flows has been estimated to be 0.9 percent at the Paso Robles
gaging station. Project specific flow reductions are not expected to be
significant. However, the cumulative effects of the overall surface water
diversions and groundwater withdrawals by all downstream users could be
considered significant.
Mitigation: Continued operation of the reservoir under the terms of the "live stream
agreement" will minimize potential impacts to downstream water users
and aquatic resources.
Many other areas for potential impacts, such as air quality, visual/aesthetics, traffic circulation,
noise, etc., were evaluated and found to have insignificant residual impacts.
EIR Certification/Notice of Determination
Normally, environmental impact reports identify specific plans for implementing mitigation
measures to reduce significant project-related impacts to acceptable levels or make findings of
overriding considerations concerning unmitigatable project-related impacts. The EIR includes
specific measures and strategies for reducing the significance of project-related impacts, but
detailed plans for implementing and monitoring mitigation measures have not been developed
yet. Since additional environmental work must be done to allow the property transfer to occur,
staff suggests developing specific mitigation plans as part of the preparation of the additional
studies, which will require consultations with various regulatory agencies. These agencies will
also be consulted to obtain the necessary permits to allow for construction of the project. The
Council can certify the EIR following the public comment period and preparation of the final
report, but the "notice of determination" will not be filed until the specific mitigation
implementation and monitoring plans have been finalized and the additional studies required for
compliance with the National Environmental Policy Act (NEPA) are completed.
CONCURRENCES
The Community Development Department has reviewed the draft environmental impact report
and concurs with the findings identified in the report.
FISCAL EMPACTS
There are no fiscal impacts associated with the certification of the EIR.
Attachment: 1. Steps to Project Implementation 4—
Attachment 1
SALINAS RESERVOIR EXPANSION PROJECT
Steps to Project Implementation
The following list identifies the major steps towards project implementation and the estimated
(optimistic) completion date for each activity.
Optimistic Completion
Date
■ Council Certification of EIR March 1994
■ Execution of Agreements between City and County May 1994
■ NEPA Environmental Assessment / Additional Studies December 1994
■ Special Federal Legislation to Allow Property Transfer January 1995
■ Transfer of Ownership June 1995
■ Design, Permitting and Mitigation Plans January•1996
■ Begin Construction May 1996
■ Construction Complete May 1997
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