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Important Data Resources
This section of the web site is devoted to facts. We
have assembled as much useful data as we have been able to find and
posted it here. Occasionally when the data speaks for itself we
will provide those conclusions as well. For opinions check our
Political Action section.
We have assembled data in the following areas:
Water level and rainfall
Water quality
Westside Basin hydrogeology
Fauna & flora
History and land use
Web statistics
Water level and rainfall
Emissions pathways, climate change, and
impacts on California (pdf file)
This
analysis, which has been widely reported in the media, was conducted by a team of 19 researchers, and appears in
the
Proceedings of the National Academy of Sciences. It's projections
for the amount of water available in California over the course of the
next century, with and/or without prompt action to curtail emission of
greenhouse gases, is most alarming. Its implications for
relying on "surplus system water" as a sustainable solution for
maintaining Lake Merced are clear. We have also
provided a summary of the implications of this analysis, prepared
by Michale Hanemann, Director, California Climate Change Center,
University of California, Berkeley.
Lake level and rainfall
data, monthly from May 1996
This page presents data in both chart and table
formats. For data that you can more easily analyze choose one of
the Excel files listed below. (The South Lake gauge has been out
of service for nearly a year now. While repairs are being made,
we have been unable to secure a current record of lake level from the
Public Utilities Commission.)
Change in lake level with
rainfall data from September 1999
Since 1999 the lake has
experienced a renewed
downward trend in spite of near normal rainfall. We have tracked
this on a separate chart that illustrates the decline of lake level
that can be expected without continued addition of Hetch-Hetchy
water.
N.B. Beginning in Summer 2003 the Public Utilities
Commission has undertaken a program adding water to the lake. We
have not continued to post lake levels, but leave this chart in place
to indicate recent experience, about a 1-foot decline in lake level
annually, without such additions.
Lake level vs. 10-year average rainfall from
1962
We have observed a good
relationship between lake
level and the prior 10-year average rainfall. This page plots
that relationship for the past 40 years, pointing out the failure of
the lake to respond to increased rainfall after the drought of the
mid-nineties.
Lake
level and rainfall, monthly data from 1996 (Excel)
Monthly lake level and
rainfall data from 1979 (Excel)
Annual lake level and
rainfall data from 1951 (Excel)
Monthly readings of rainfall
taken at SFO from 1950 (Excel)
Water quality
Quarterly readings of key
quality parameters from February 1997 (Excel)
Dave Dingman, chemist with the
Water Department in
Milbrae, has taken quarterly water quality readings at Lake Merced for
more than five years. These are presented here in both tabular
and graphic
format.
For the past
several months (as of February 2005) there have been unprecedently high
readings of E-coliform bacteria, at first in North Lake and more
recently in South Lake as well. (See reports in Political
Action.)
Fortunately, very high readings of E-coli
bacteria reported in North Lake for December 2004 proved to be the
result of a scaling error that magnified the actual count
tenfold. However, this error brought new focus on the need to
develop a practical yet effective monitoring program to protect the
health and safety of the lake's many users.
Plankton and Ammonia readings seasonally
indexed
Lake
Merced Hydrology and Water Quality, by Vivian Matuk and Nick
Salcedo, Graduate Students in Geography, San Francisco State University
Westside Basin hydrogeology
Technical
Memorandum TM-18, published as a part of the San Francisco
Groundwater
Master Plan (1967) describes a model of the Westside Basin developed by
the consulting firm CH2M Hill using the MicroFem simulation tool.
Table A provides a detailed description of
both monitoring and production wells in the Westside Basin. (Excel
file) The accompanying text describes
the data collection procedures.
Table B describes land use, including per cent
irrigated, and per cent impervious surface. (Excel file)
Again, the accompanying text describes the
data collection procedures.
Geology
and Hydrogeology of Lake Merced, San Francisco, California, by
Yu Shimuzu, Graduate Student, Geography, San Francisco State University
The
Climatology of Lake Merced, San Francisco, California, by
Graeme Somerville. Graduate Student, Geography, San Francisco
State University
Fauna and flora
Field
Surveys: Technical Memorandum (Draft), EDAW, February 5, 2003 (pdf
file, 6.5MB)
Complete listing
of birds both nesting and
visitors at Lake Merced
Annual
bird surveys: 1999 2001
Invertebrate
Fauna at Lake Merced, by Nelia White, Graduate Student,
Geography, San Francisco State University
Birds
of
Lake Merced, by Doug Johnson, Graduate Student, Geography
San Francisco State University
Fish
Species of Lake Merced, by Ian Singer, Graduate Student,
Geography, San Francisco State University
Mammals,
Reptiles and Amphibians of Lake Merced, by Elizabeth J.
Proctor, Graduate Student, Geography, San Francisco State University
The
Flora at Lake Merced, by Juan Ochoa, Christopher Campbell, and
Paul Pribor, Graduate Students, Geography, San Francisco State
University
History and land use
The
History of Human Use at Lake Merced, by Sara
Marcellino and Brandon Jebens, Graduate Students, Dept of Geography,
San Francisco State University
Web statistics
We continue to be pleased with the interest in
Lake Merced. Check the number of visitors to this site each month.
Model Monitoring Program for Municipal Separate Storm Sewer Systems in Southern California, A report from the Stormwater Monitoring Coalition’s Model Monitoring Technical Committee, August 2004
The California Department of Health Services (Draft) Guidance for Freshwater Beaches.