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| Willie
L. Brown, Jr.
Mayor Ann Moller Caen
E. Dennis Normandy
Patricia E. Martel
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May 13, 2002
Mr. Dick Morten
Subject: Lake Merced Questions Dear Mr. Morten: I am writing in reply to our e-mail dated March 31, 2002 regarding questions about Lake Merced. |
| Your first set of questions revolved around the potential for immediate
water additions to Lake Merced. The first question was regarding
addition of water to Lake Merced and Pine Lake now as part of an experiment
for better understanding the hydrology. I contacted our consulting
hydrologist, Joe Scalmanini, regarding the additions of water and the potential
effects it might have on the lake and underlying aquifer. He has
stated that direct additions are the quickest and most effective way to
raise lake level. We are preparing a technical memorandum of the
initial estimate of amount of water to raise Lake Merced levels by 2 to
8 feet. The rate of fill is limited by our ability to discharge excess
imported surface water into the lake. In addition, we are attempting
to estimate the amount of water that would be needed once the target level
is reached to maintain lake levels for subsequent losses (i.e. evaporation
and groundwater seepage). This could be expressed as an annual, seasonal
or daily re-fill rate. We are also exploring timing and availability
of resources when examining the issue of filling the lake.
The cost to discharge excess regional water to Lake Merced is limited to the cost of chemicals to neutralize the chlorine in the water and some incidental operation staff charges. The cost is approximately $150 - $200 per million gallons. When we make these statements regarding costs, we are assuming that all our customers needs are being met, there are no significant operational constraints and it is water that is excess to our needs or would be lost from the system (i.e. spill from the system). The Commission sets the general policy direction regarding the desirability to discharge water to the Lake. The decision to discharge water to Lake Merced rests with the General Manager since it is affects (sic) the daily operation of the water system. The timing of such discharges is also dictated by regulatory approvals and other mitigating measures. You inquired how we obtain a permanent allocation of water for Lake Merced and Pine Lake. I am assuming that the permanent allocation would be imported make such an allocation. (sic) We are exploring the possibilities of other sources such as reclaimed water and storm water as a dedicated supply to the lake. We are looking into the regulatory constraints of discharging chloraminated water to the Lake or the shallow aquifer. Once we have this information we will forward it to you. In regards to recycled water from the Daly City plant, we could purchase winter tertiary recycled water from Daly City to put in Lake Merced. The SFPUC contribution to Daly City's plant was for construction purposes only. The recycled water production primarily would be for the spring through fall irrigation season for the three golf courses. Daly City's operating expenses and price negotiated with the three golf courses is based on that production scenario. The availability and costs to San Francisco for the winter production has been discussed and we continue to discuss it with Daly City. Besides the price of water, it would require additional piping and environmental permitting in order to discharge recycled water to the lake. We are currently updating the San Francisco recycled water plan and would be glad to share that with you when completed. If it is convenient, perhaps we can get together to share with you our ideas on how to proceed before we complete the update. We are also re-examining recycled water potential in the entire wholesale service area as an alternative to close the gap in water resources needed for the future. San Francisco was one of the founding members of the Bay Area Regional Water Recycling Program that identified recycled water potential in the entire bay area. We continue to promote recycled water as a tool to diversify our water resources portfolio. Please contact me so that we may set a time to meet on recycled water and any other areas of water resources interest. You can contact me at (415)934-5787. Sincerely, (signed) Michael P. Carlin
Cc. Patricia E. Martel, General Manager, SFPUC
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