LAKE MERCED: Initiative to Raise and Maintain Lake Level and Improve Water Quality;

Task 3 Technical Memorandum, Draft for Public Review and Comment
August 2003

The following constitute the comments of the Golden Gate Audubon Society regarding the document named above.  The Golden Gate Audubon Society is a grassroots conservation organization with a membership in San Francisco, Oakland, Berkeley and much of the rest of the Bay Area.  Through our field trips, newsletters, programs and public comments we have educated the public, advised public agencies and documented the presence of birds and mammals at the lake for 84 years. The Golden Gate Audubon Society is located at 2530 San Pablo Ave., Suite G, Berkeley, CA 94702.  Our telephone number is (510) 843-2222.

We find this technical memorandum lacking in a number of ways.  There are numerous errors in identifying graphics that make it very confusing and difficult to read.  Failure to include a glossary for some of the technical terms and abbreviations is another factor limiting the readability of this document.  For those reasons it should be rewritten and submitted to the public in a corrected form.  We believe there are substantive errors such as the modeling discussion on page 34.  Also, there are errors of omission such as the failure to discuss treatment of chloramine in recycled water.  We have included a number of recommendations through the text of our comments which we hope will add to the value of this document.

EXECUTIVE SUMMARY

p. iii. Existing Lake Water Quality: The second sentence is of questionable accuracy.  We concur that the present water conditions result in algae growth and poor habitat for some aquatic species, but certainly not all.  For example, present conditions seem to favor Clark's Grebe. It would be best to mention a few aquatic species that are negatively impacted by present eutrophic conditions.

It would seem appropriate to identify when eutrophic conditions would normally occur at Lake Merced. When water levels were considerably higher, eutrophic conditions did occur by late summer and during September and October.  It should be pointed out that increasing water level will only shorten the period for conditions that result in eutrophic conditions.

The second to last sentence should be amended to mention that South Lake is also larger than North Lake, and with considerably greater water volume it has suffered a little less from high nutrient levels.  It is likely the geographic position of South Lake somewhat reduces nutrient levels.

p. iv. Groundwater:  In the section discussed from p. iii it is stated, "the conditions can be accelerated by the introduction of nutrients in stormwater, groundwater, or other inputs."  However in this section it is stated that "Treatment of groundwater prior to discharge to the lake would not likely be necessary as ground water in the lake area is assumed of similar quality to that already discharging to the lake." This seems to be a contradiction. Any groundwater released into the lake should be tested, monitoring should be ongoing, and treatment should be made available if necessary.

GGAS RECOMMENDATION: p. v.  We need to add an additional element to thisdocument right here, before we get into the details of the memorandum.  Here should be added a statement regarding adaptive management.  Details of the adaptive management plan should be incorporated into the body of the document and should focus at least on several indicators including water quality, marsh healthy, bird life, health of the fishery, studies of specific insect species and other relevant indicators suggested by others.

p. 2.  Once again we must question the reasoning behind the selection of 26 feet as the optimal level for the lake.  This may in fact be the ideal level for the lake.  It may not. This would be a good place to identify the scientific reasoning used by Geo/Resources in determining this as the best level for the lake.

p. 4  a) History:  The document cited from Archaeological Consultants, 1981 is not cited in the Bibliography.  That should be corrected.

p. 6:  The "Impound Lake", as it has recently come to be known, was never planned and it wasn't separated by the constructed of the concrete bridge.  To our knowledge the "berm" was constructed by wind and wave action that caused drifting sand from the lake bottom to pile up around the piers for the bridge.  The original structure spanned the lake but allowed water to flow beneath it.  South Lake remained complete until the water level dropped during the 80s.  Water was deep enough on both sides of the bridge to allow people to fish from it.  This statement should be rewritten.

p. 7,  paragraph 1:  The zoo still pumps water from the aquifer.  They just built new wells a few years ago.

       Paragaraph 2, last line:  It might be better to use the term "birding" instead of "bird watching".

p. 9. ii) Topography: It would be helpful if a description of the vegetation buffer between the perimeter path and the water's edge were included here.

p. 10. Geology:  This first paragraph is unclear.  Are you saying the relationship between the Colma and Merced Formations generates interest but there is no real knowledge about that relationship?  It that's so, it should be stated.

p.12.  iii)  Geology:  The locations of the cross-sections are not illustrated in Figure 3-1.  There is no Figure 3-1.  Not only that, there is no such illustration under any number.

p.16.  last paragraph:  What does this mean?  I take it to mean the length of time a hypothetical H2O molecule stays in the lake before evaporation or going into the aquifer.

p. 17.  vii) Pathway and Trails:  This is understated.  A trial connects the wood foot-bridge below the Sunset Circle to Harding Park and public use is such that Harding Rd. is a foot trail and is supposed to be formalized in the new Harding Golf Course project.  There are several formal and informal trails elsewhere around the lake.

          viii) Boat Launch:  Actually there is boat launching is available into both North and South Lakes via docks, ramps and informal access sites elsewhere.

          ix) Fishing Piers: This is slightly misleading. It should say the fishing pier at the southwest end of South Lake is being replaced.  This section too should identify all fishing piers specifically.  For example, the Hass Pier should be named and the site should be identified simply to identify points of public access to the lake.

           x) Fishing Beaches: How did you miss this?  They exist now and historically at the North Lake below the Sunset Circle, at the picnic area by the Harding Rd entrance and on the south lake on both sides of the concrete bridge/sewer.  This is critical to include because like in ix) above, it identifies points of public access to the lake.

P. 20  Physical Characteristics:  The last 4 items at the bottom of the page appear to be questionable.  Our understanding of stratification is that it is a desirable condition in a cold water lake because wind conditions do not churn water below about 27 feet.  Thus cold water remains deep in the lake, fish such as trout can take refuge there, different organisms exist there and it essentially adds to the viability of the lake.  Also, as one who uses the lake several times a week, it seems highly questionable whether "extended calm conditions" exist at Lake Merced. There is seldom a day without wind on the South Lake at least.

GGAS RECOMMENDATION: At this point it would be very positive to discuss the matter of stratification.  At what point does stratification occur?  Is it desirable?  Without stratification, what are the benefits of adding water to the lake? This is the point where a scientific explanation for adding water to a specific range of depths should be made. It seems the prior statement of 26 feet should be dropped in favor of a range which can be sustained over an annual cycle.  Note here we are not favoring any specific depth, but a range which might simulate a natural cycle and reduce the ongoing expense of constantly adding water and creating unnatural conditions.

p. 27.  v) Trophic Status:  Table 2-4 is the wrong table.  I guess it's supposed to be 2-3.  Did anybody proof read this document?

The last sentence of that first paragraph is very unclear.  "An order of magnitude" means nothing to me, and I would suggest it means little to many others.  Perhaps a different descriptor could be used.

GGAS RECOMMENDATION: This brings to mind a constant problem with this document, there is no glossary.  If public review is welcomed, the document should be written in such a way that the general public can understand it clearly.  How many people might understand terms like "dissolved oxygen", "order of magnitude", "trophic", or "eutrophic" to name only four.  Addition of a glossary would certainly increase the readability of this document.

p. 29.  e) Water Quality of Existing Inflows: Section 4b is not on pg. 43 but it is on pg. 42.

The last paragraph states: "Lake Merced is presumed to be directly connected with the shallow aquifer system."  Presently, at what level of certainty are we?  What would it take to confirm or refute this?

Then the paragraph goes on, "Ground water thus represents a significant nitrogen source that can exacerbate eutrophication."  Doesn't this suggest we can't use ground water to enhance lake water? If we can it would seem to require treatment.  That contradicts previous statements.  We need clarification here.

p. 34.  i) Model Results:  The paragraph that begins "Total volumes:" suggests that water increases will take place over a single year.  That is not part of any plan of which the Golden Gate Audubon Society is aware and we would like to know the origin of the plan and just how it will be accomplished in terms of habitat protection.  Since the Department of Fish and Game and GGAS have long stood for a graduated raising of lake levels, not unlike what has happened in the past year, I must say we are quite stunned to see reference to a model that adds the maximum amount of water in a single year.  On looking at Tables 4-3 and 4-4 we find we were misled once again. Tables 4-1 and 4-2 seem the correct tables and they seem to contradict the whole reason for our concern. Just what is going on here? The text states, "These figures show that after the first year of water addition less supplemental water is required to achieve equivalent lake level increases.  Less water is required because the first year included the initial raising of the lake level and subsequent years require a smaller lake level increase."  That certainly seems to say lake level is going to be raised all at once and then maintained.  Further, it does not seem to be supported by Figure 4-1 and 4-2.  Perhaps this is just an error in editing and can be changed in a subsequent report.  Otherwise the model in question will require major mitigation that should be discussed at this point.

p. 41.  ii) Vista Grande Stormwater:  First paragraph =AD not Table 4-6 and 4-7, but Table 4-8 and 4-9?  Do you really get paid for doing this?

p. 46. v) Summary:  This summary should be substantive.

p. 51  b) Response of vegetation to rising water levels:  One modeling reference that could be used to suggest revegetation patterns would be to reference historic photos.  This might suggest areas where mitigation is possible and others where it is not.  The lake's edge was completely altered with construction of Skyline Blvd. and Harding Park in the late 20's and with subsequent efforts to increase water volume.  The marsh was removed at one point and reestablished itself naturally.  The pattern of that reestablishment should prove valuable in mitigating impacts of increasing water levels.

GGAS RECOMMENDATION: A significant factor related to vegetation around the lake is the buffer zone between the perimeter road and the open water.  This is an significant habitat consideration because increased water levels will reduce and alter wetland and upland habitats.  It needs to be modeled so we have a better sense of potential impacts.

p. 54.  a) Recycled Water:  Where would the treatment wetland for nitrate removal be? What would it's impact be on wildlife?

This section is incomplete.  There is no mention of treatment of water for chloramine.  Once local water is chloraminated, it can no longer be directly pumped into fresh water lakes.  We understand the reason for this is that the ammonia in this chemical doesn't breakdown or evaporate.  Recycled water would seemingly still need to be treated to eliminated residual chloramines.

GGAS RECOMMENDATION: Add the necessary section regarding the treatment of recycled water to rid it of residual chloramonia.

p. 57.  d) Westside Basin Groundwater:  In reference to the second bulleted item, please see our comments regarding p. 29.  Just how can nitrogen enriched water be placed in a eutrophic lake and not "exacerbate eutrophication" without treatment.  We can't have it both ways, which one is it so we can comment.

The last bulleted item on this page need much more development and discussion.

This concludes the comments of the Golden Gate Audubon Society.

Daniel P. Murphy
Conservation Committee
2945 Ulloa St.
San Francisco, CA 94116
(415) 564-0074
murphsf@comcast.net
murphf@yahoo.com