Comprehensive Management Plan for Lake Merced
WATER RESOURCES PROGRAM
Lake Merced is managed as an alternative water resource to be used during an emergency primarily for fire and sanitary control and secondarily for potable use. Since 1949, lake level at Lake Merced has been declining. Lake level declineis the result of the combined effects of multi-year droughts, urbanization, and increased groundwater usage. Lake level decline is a serious concern for two reasons (1) it degrades the Lake’s water quality and (2) it threatens the City’s surface and groundwater resources.
To successfully protect and enhance the water resources of Lake Merced, the following goals and Actions Items have been identified and developed.
The Water Resources Program Area Goals and Action Items are:
Goal 1 Maximize Water Level for Appropriate, Identified Beneficial Uses
Action WRS-1.1 Review the Lake’s “Emergency
Water Supply” Status
Action WRS-1.2 Review Identified Beneficial
Uses
Action WRS-1.3 Conduct a Natural Resources
Survey and Assessment Report
Action WRS-1.4 Develop and Evaluate
Alternatives for Increasing Lake Level
Action WRS-1.5 Discharge Surplus Imported
Surface Water to South Lake
Action WRS-1.6 Develop a Condition Assessment
of the Import/Export Infrastructure of Water to Lake Merced at Lake Merced
Pump Station
Action WRS-1.7 Develop a Lake Merced Emergency Operations Plan
Goal 2 Preserve the Lake’s Integrity and Its Relationship With the Underlying Aquifer
Action WRS-2.1 Manage the Westside Groundwater
Basin
Action WRS-2.2 Install Lake Level Gauges
on North and Impound Lakes
Action WRS-2.3 Supply Groundwater Users
with Surface Water During Wet Years
Action WRS-2.4 Encourage Groundwater
Conservation Efforts
Action WRS-2.5 Encourage Natural Recharge
of the Aquifer
Action WRS-2.6 Implement Groundwater
Monitoring in the Vicinity of Lake Merced
Action WRS-2.7 Encourage the Use of
Recycled Water
Goal 3 Protect and Enhance Water Quality for the Appropriate, Identified Beneficial Uses
Action WRS-3.1 Conduct a Lake Merced
Watershed Sanitary Survey
Action WRS-3.2 Implement Storm Water
best Management Practices Along Lake Merced Boulevard, John Muir Drive,
and Skyline Boulevard (Highway 35)
Action WRS-3.3 Conduct a Pollution Prevention
Demonstration Project
Action WRS-3.4 Develop and Conduct a
Quarterly Limnological Monitoring Program
Action WRS-3.5 Investigate Fish Conditions
WATER RESOURCES PROGRAM
Goal 1 Maximize Water Level for Appropriate, Identified Beneficial Uses
Action: WRS-1.1 Review the Lake's "Emergency
Water Supply" Status
Who: SFPUC, Bay Area Water Users Association
Why: SFPUC is developing a Water Supply Master
Plan ("WSMP") to develop an overall plan to meet projected future needs
of the service area through coordinated use of available surface water,
groundwater and recycled water resources; conservation of existing supplies;
development of alternative resources; and management of water demands,
where feasible. As an emergency water resource, Lake Merced appears
to be an important component in the SFPUC water supply. During the
development of the WSMP, Lake Merced's current status and its future contribution
to groundwater recharge and emergency water supply needs will be reviewed.
What: Review the status of Lake Merced as
an "emergency water supply" and recommend a status consistent with the
goals and of the WSMP.
When: Spring, 1997 to Summer, 1998
Funding: SFPUC
Cost: $20,000
Action: WRS-1.2 Review Identified Beneficial
Uses
Who: SFPUC
Why: If the status of Lake Merced as an "emergency
water supply" is changed as part of the WSMP (WRS-1.1), various beneficial
uses identified at the beginning of Lake Merced CMP may be modified.
What: Review and revise the currently identified
beneficial uses to ensure that they are consistent with the Lake's status
and its water quality objectives.
When: Fall, 1998 to Winter, 1999
Funding: SFPUC
Cost: $10,000
Action: WRS-1.3 Conduct a Natural Resources
Survey and Assessment Report
Who: SFPUC, SFRPD
Why: Current resource (i.e., plant, wildlife,
fisheries) data at the Lake are needed to assess the impact of changing
lake level on the natural resources and to recommend a range of appropriate
lake levels consistent with the beneficial uses.
What: Conduct a natural resources survey and
assessment report which includes (1) a seasonal inventory of natural resources;
(2) an assessment of the condition of each resources's habitat; (3) water
quality standards and optimum lake level ranges for each resource; and
(4) a comprehensive analysis of water level and quality versus resource
habitat. (Coordinate with action NRE-1.1.)
When: Winter, 1998 to Winter, 1999
Funding: SFPUC
Cost: $35,000
Action: WRS-1.4 Develop and Evaluate Alternatives
for Increasing Lake Level
Who: SFPUC
Why: The Lake Merced Water Resource Planning
Study, May 1993, recommended that a lake level of 26 feet (referenced to
the Lake Merced PUmp Station gauge board, also 17MSL) "would gnerally satisfy
most beneficial uses and would improve some water quality characteristics".
Based upon this recommendation, develop alternatives for increasing lake
level to within an acceptable range of 26 feet.
What: Conduct an alternatives study.
Develop five alternatives to raise lake level to within an acceptable level
of 26 feet, include an evaluation of the feasibility, benefits and costs
associated with each alternative. Alternatives to be considered include
addition of water directly to the Lake, injection of the water into the
adjacent aquifer, andmodification of local pumping. Sources of water
to be considered include imported surface water, recycled water, desalinated
water, and storm water. (Coordinate, WRS-2.1 and WRS-2-6).
When: Fall, 1998 to Fall, 1999
Funding: SFPUC
Cost: $80,000
Action: WRS-1.5 Discharge Surplus Imported
Surface Water to South Lake
Who: SFPUC
Why: In recent years, urbanization, drought,
and increased groundwater pumping have contributed to declining lake level
and water quality at Lake Merced. Recently, an agreement between
the California Department of Fish & GAme and the Audubon Society with
SFPUC allows for the discharge of water into the Lake from mid-July through
mid-April. (See Appendix G, "Certification of Determination of Exemption/Exclusion
from Enfironmental Review"). The Certificate defines a water discharge
schedule which protects the bird nesting season at the Lake.
What: During normal and wet years, when the
SFPUC has surplus water supplies, discharge decholorinated imported surface
water to the Lake.
When: Spring, 1997 to Spring, 2002
Funding: In City-rate payers
Cost: 0.77 $/Ccf of water
Action: WRS-1.6 Develop a Condition Assessment
of the Import/Export Water Infrastructure for Lake Merced at the Lake Merced
Pump Station
Who: SFPUC
Why: At present, imported surface water is
periodically decholorinated and discharged to Lake Merced at the Lake Merced
Pump Station. However, this operation requires one of the City's
supply pumps to be off-line. While this method is acceptable for
short discharge periods (i.e., one to three weeks), it is unacceptable
for longer periods as it puts the City water supply at risk. If Lake
water were to be exported during an emergency for potable use, the water
would need to be chlorinated and, ideally, filtered. Currently, the
only filter system consists of two coarse screening drum filters, and no
permanent chlorination system exists on the site.
What: Conduct a condition assessment report
of the Lake Merced import/export water infrastructure. Develop an
alternatives study to identify improvements and alternatives to the import/export
delivery systems. (Coordinate with WRS-1.1)
When: Summer, 1998 to Winter, 1999
Funding: SFPUC
Cost: $50,000
Action: WRS-1.7 Develop a Lake Merced Emergency
Operations Plan
Who: SFPUC
Why: While Lake Merced is identified as an
"emergency water supply", no Lake Merced emergency operations plan exists.
An emergency operations plan is needed which would (1) identify when it
would be appropriate to begin transporting Lake waters into the City's
distribution system; (2) define the required treatment process and operation;
and (3) detail the appropriate public notification requirements.
What: Develop a Lake Merced Emergency Operations
Plan
When: Fall, 1998 to Winter, 1999
Funding: City Distribution Division
Cost: $30,000
Goal 2 Preserve the Lake's Integrity and Its Relationship With the Underlying Aquifer
Action WRS-2.1 Manage the Westside Groundwater
Basin
Who: SFPUC, California Water Service, City
of Daly City, and City of San Bruno
Why: The Westside Groundwater Basin supplies
groundwater to many potable and non-potable users. These users operate
independently. Because the Westside Groundwater Basin is a shared
resource and overuse of the basin can have a cumulative negative impacts,
cooperative management is important to the common long-term benefit of
all the basins users. With respect to Lake Merced, long-term negative
impacts on the aquifer affect Lake Merced because it is hydraulically connected
to the groundwater basin.
What: Develop a Westside BAsin Management
Plan. A 1992 State law, AB 3030, encourages and provides the framework
for local public agencies to jointly manage shared groundwater basins.
SFPUC has entered into an agreemetn with the City of Daly City, California
Water Service, and the City of San Bruno to develop a Westside Basin Management
Plan which will address common issues such as, (1) the control of saline
water intrusion, (2) theidentification and management of wellhead protection
and recharge areas, (3) the monitoring of groundwater levels and storage,
and (4) the monitoring and protection of the groundwater quality.
When: Sprint, 1997 through Summer, 1998
Funding: SFPUC/Groundwater Development
Cost: $160,000 (total); $40,000 (SFPUC's share)
Action WRS-2.2 Install Lake Level Gauges on
North and Impound Lake
Who: SFPUC
Why: To further the understanding of the Lake's
relationship with the Westside bAsin, it is important to monitor lake level.
Currently only South Lake level is monitored. In addition, fisherpersons
want a viable water gauge in all lakes as lake level affects the quality
of fishing.
What: Install lake level gauges on North and
Impound Lake
When: Fall, 1997
Funding: SFPUC
Cost: $2,000
Action WRS-2.3 Supply Groundwater Users With
Surface Water During Normal and Wet Years
Who: SFPUC
Why: During normal and wet years, the SFPUC
has excess surface water. Routinely this water is discharged to local
rivers and streams. However, if this water could be supplied to a
groundwater user, then the groundwater user could reduce its groundwater
pumping during this period. SFPUC is negoitating with the City of
Daly City to supply their water demands during normal and wet years with
imported surface water; and accordingly, City of Daly City will reduce
its groundwater pumping by during the same period.
What: Develop surface water in-lieu of groundwater
use agreements with local groundwater pumpers. Use the proposed City
of Daly City agreement as a precedent for developing in-lieu agreements
with other groundwater pumpers.
When: Fall, 1997 and on-going.
Funding: SFPUC/Groundwater Development
Cost: TBD
Action WRS-2.4 Encourage Groundwater Conservation
Efforts
Who: SFPUC, Westside Basin Users
Why: Quality of life an dthe health of the
environment depend in large part upon the water resources of teh bay Area.
Increasing demands for urban and environmental water uses call for conservation
and the eliminatoin of waste as important elements in the overall management
of water resources. Lake level is especially sensitive to drought
periods. Consequently by reducing demands on teh local aquifer during
periods of drought, it will help contribute to the overall health of the
basin and the Lake.
What: Encourage local governments to participate
in the Memorandum of Understanding Regarding Urban water Conservation in
California.
When: Fall, 1997 and on-going
Funding: SFPUC
Cost: $50,000
Action WRS-2.5 Encourage Natural Recharge of
the Aquifer
Who: SFPUC, Westside Basin Users
Why: Urbanization and its rsultant construction
of roads and parking lots has increased the amount of land that is covered
with impervious surfaces thus preventing stormwater runoff from percolating
down and rechargin the aquifer. Additionally in the City, stormwater
is diverted to the sanitary sewer and increases the load on SFPUC water
pollution control facilities. Aloternative landscaping designs, including
the use of greenbelts, permeable roadways and parking lots, could help
to increase the inflow rates to teh aquifer and decrease th eload on the
water pollution control facilities.
What: Encourage alternative landscaping designs
which reduce the amount of impervious surface area above the basin, for
example, the redesign of the San Francisco Zoo parking lot. Investigate
alternative stormwater treatment technologies to facilitate the use of
stormwater runoff for aquifer recharge. (Coordinate WRS-3.2)
When: Fall, 1997 and on-going
Funding: SFUC
Cost: $25,000
Action WRS-2.6 Implement Groundwater Monitoring
in the Vicinity of Lake Merced
Who: SFPUC
Why: Lake Merced is closely linked to groundwater
levels in the Westside Basin. Monitoring groundwater extraction rates
at production wells and groundwater levels in monitoring an dproduction
wells near Lake Merced will provide important information regarding the
relationship of changing Lake levels to groundwater conditions. This
will be especially important when assessing the actual impacts to groundwater
levels resulting from the planned Sunset District wells and the planned
increase in production at the San Francisco Zoo. It is also significant
for evaluateing the effectiveness of strategies to raise the level of Lake
Merced.
What: Routinely (quarterly) measure water
levels in existing monitoring and production wells and install three additional
monitoring wells (two north and one east of Lake Merced). Collect
water level data more frequently (daily, weekly, monthly) as new wells
are installed andinitially operated. Collect data, where possible,
from local groundwater users regarding the operation (and flow volumes,
if available) of their production wells. Train existing Lake Merced
maintenance staff to collect quarterly water level data.
When: Winter, 1997 and on-going
Funding: SFPUC
Cost: Installatin of 3 monitoring: $50,000.
Sampling & Analysis: $2,000 (quarterly)
Action WRS-2.7 Encourage the Use of Recycled
Water
Who: SFPUC
Why: The City has prepared a Recycled Water
Master Plan which proposes a number of uses of recycled water within the
city. One potential use is th emeeting of non-potable demands of
Golden Gate Park, the Presidio and the Zoo. Recycled water can also
be used to prevent saltwater intrusin and to increase groundwater recharge.
Recycled water is also a potential water source for Lake Merced.
What: Continue the exploration of recycled
water to reduce groundwater extraction and to prevent saltwater intrusion
in the Westside Basin.
When: Fall, 1997 and on-going
Funding: SFPUC
Cost: TBD
Goal 3 Protect and Enhance Water Quality for the Appropriate, Identified Beneficial Uses
Action WRS-3.1 Conduct a Lake Merced Watershed
Sanitary Survey
Who: SFPUC
Why: A watershed survey will provide a detailed
"snapshot" of the condition of each element of the living system of the
Lake and will provide a basis to monitor and quantify changes to the system.
A Watershed Sanitary Survey will include the following information: characterization
of the watershed and water supply system, potential contaminant sources,
watershed control and management practices, water quality. The Watershed
Sanitary Surveywill also be used in the Water Supply Master Plan to review
Lake Merced's status. (Coordinate with WRS-1.1)
What: Conduct a watershed sanitary surveyin
accordance with the "Watershed Sanitary Survey Guidance Manual", prepared
by the American Water Works Association, California/Nevada SEction, Source
Water Quality Committee, August, 1993.
When: Sprint, 1998 to Fall, 1998
Funding: SFPUC/Groundwater Development
Cost: $50,000
Action WRS-3.2 Implement Storm Water Best Management
Practices along Harding Park Road, Lake Merced Boulevard, John Muir DRive,
and Skyline Boulevard (Highway 35).
Who: SFPUC, DPW, DP&T, Caltrans
Why: Storm water runoff is part of the natural hydrological
process. Howevere, human activities and urbanization can alter natural
drainage patterns, negatively change the quality of the runoff, and reduce
the amount of recharge to the underlying aquifer. Storm water runoff
can be a significant source of water pollution. I order to control
the amount of pollution from storm water runoff entering Lake Merced, it
is necessary toimplement practices which will reduce or eliminate debris
and pollutants entering the Lake from perimeter roads and the landscape.
What: Implement Source Control and Treatment Control Best
Management Practices, as apprpriate, from the "California Storm Water Best
Management Practice Handbook, Municipal", March, 1993
When: Winter, 1998 and on-going
Funding: SFPUC
Cost: TBD
Action WRS-3.3 Conduct a Pollution Prevention Demonstration
Project
Who: SFPUC
Why: Currently, approximately 90% of the storm
water runoff from the Lake's perimeter roadways and adjoining parking areas
are discharged, untreated, into the Lake. The remaining 10% of the
storm water flows drain to the sanitary sewers. The storm water runoff
entering the Lake contains oil/grease, heavy metals, and petroleum hydrocarbons.
What: Conduct a pollution prevention demonstration
project to determine the effectiveness of an emerging technology to pretreat
storm water runoff contaminated with oil/grease, petroleum hydrocarbons
and/or heavy metals. The purpose of this demonstration project is
(1) to identify a technology capable of providing pretreatment of storm
water flows upstream of the City's water pollution control facilities,
(2) to identify technologies which can protect surface waters from contaminated
storm water, and (3) to advance the science of treating storm water runoff.
The long-term goal of this demonstration project is to identify a storm
water pretreatment method that could be utilized throughout San Francisco
in parking areas, along roadways, and in automotive facilities.
Use the catch basin in the north Harding Park Road parking lot as the site to test the effectiveness of the CSF Stormwater Treatment System ("CSF"). The CSF System is a compost filter system designed to use a specially processed leaf compost that has been pelletized and placed into filter cartridges that are inserted into pre-cast concrete vaults. Simlar compost filters have been shown effective at removing about 80% of oil and grease, 84% of petroleum hydrocarbons, and 65-83% of heavy metals typical of parking lots.
This demonstration site was chosen because the identified storm wate
catch basin receives storm water runoff primarily from th eparking area,
the western section of Harding Park Road, and a limited amount of flow
from Skyline Boulevard (Highway 35). Catch basin flows will be directed
to the CSF. Treated runoff will be drained to a collection pipe and
discharged for transport to the Lake.
When: Winter, 1997 thorugh Winter, 2000
Funding: 1994 Sewer Bonds
Cost: $80,000
Action WRS-3.4 Develop and Conduct a Quarterly
Limnological Monitoring Program
Who: SFPUC
Why: Water quality data is needed to assess
limnological conditions at Lake Merced. The data will be used to
make recommendations on ways to improve water quality and help identify
a range of appropriate lake levels. These profiles will provide water
quality data that is needed to comply with the water quality standards
for the identified, beneficial uses.
What: Conduct quarterly water quality and
limnological monitoring at the Lake. Four profiles will be prepared
for each monitoring event: one profile each for EAst and North Lakes and
two profiles for South Lake. Conduct storm water quality monitoring.
Distribute summaries of monitorng results to all stakeholders. Design,
build and maintain a Lake Merced water quality data base. SEe Appendix
H "Water Quality Monitoring At Lake Merced" (Coordinate with WRS-1.3, NRE-1.1,
NRE-1.5)
When: Winter, 1997 and on-going
Funding: SFPUC
Cost: $1,250 quarterly
Action WRS-3.5 Investigate Fish Conditions
Who: SFPUC
Why: Local fisherpersons have reported that
the fish from the North Lake taste distinctly different from the fish of
South Lake. There have been numerous undocumented reports of North
Lake fish tasting "bad" and/or "muddy".
What: (1) Develop a fishing condition survey
to document and determine whether the fisherperson's fish handling practices
influence the taste of the fish. (2) Investigate envirnomental conditions
at the Lake. Monitor water quality parameters to determine if there
is an environmental condition unique to the Lake that could be affecting
the taste of the Lake fish. Investigation to include: the examination
of fish tissue to identify factors which could explain the fish taste problesm;
and identification plants or algae that could impart a taste to the fish
and determine if these plants or algae are present at the Lake. (Coordinate
with WRS-3.3, WRS-1.3, NRE-1.1 and NRE-1.5) (3) Based upon the findings
of Nos 1 and 2, recommend lake management techniques to improve the Lake
Merced fishery.
When: (1) and (2) Sprint, 1998 to Winter,
1999. (3) Spring, 1999
Funding: SFPUC
Cost: $20,000
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