July 26, 2004
File No. 02-1-094

Mr. Greg Bartow
Groundwater Program Manager
San Francisco Public Utilities Commission
1145 Market Street, Suite 401
San Francisco, Ca  94103

SUBJECT:  RESPONSE TO COMMENTS BY FRIENDS OF LAKE MERCED AND
ALLIANCE FOR A CLEAN WATERFRONT DRAFT NORTH WESTSIDE BASIN
GROUND-WATER BASIN MANAGEMENT PLAN

Dear Mr. Bartow:

In response to your request, following are responses to primarily address technically-related comments submitted by the Friends of Lake Merced and the Alliance for a Clean Waterfront on the Draft North Westside Ground-Water Basin Management Plan.  The comments were submitted in a letter dated July 15, 2004 and co-signed by Alex Lantsberg for the Alliance for a Clean Waterfront, and by John Plummer for the Friends of Lake Merced.

Notwithstanding various negative comments in the comment letter about process, the draft Plan was prepared in close coordination with SFPUC staff, and was discussed at several public meetings prior to being circulated as a draft.  As described in the draft Plan, it was prepared to conform with provisions in the Water Code for local public agencies to adopt plans to manage groundwater resources within their jurisdictions.  While the draft Plan can be revised as appropriate, the format follows standard ground-water management plan format and is, in every sense, a typical, broad plan that will generally guide ongoing and future efforts to manage SFPUC ground-water resources.  Attacks on the process are not helpful, but are outside the scope of the following responses.

There is little in the subject comment letter which can be characterized as technical comments since it focuses on the process of water resource management and on specific actions which, according to the authors, should be prioritized for analysis and implementation.  It is ironic that the Plan contains so much of what the commentors insist is needed.  For example, the comment letter criticizes that City operations are "blind", without proper data collection; Primary Plan Elements 1 and 2 address data collection on point.  The comments claim that recommendations from so-called "leading technical experts" have been ignored, and cites to the recently oft-repeated concept of injecting recycled water along the coast to retain fresh water and increase sustainable yield; that specific concept is discussed in some detail below.  The comments also state that “the only consideration of recycled water is its use for direct input into the lake; using recycled water to buttress the aquifer is off the table”.  Primary Plan Element 3 directly addresses the yield of the aquifer system, and Primary Plan Element 6 keeps open all options for appropriate incorporation of recycled water in the overall management of ground water in the basin.  As regards those two Plan elements, the management plan envisions continued, and possibly increased, use of ground water for water supply, within the yield of the basin; and the recycled Plan Element notes two likely potential uses of recycled water, but not to the exclusion of other possible uses.  Interestingly, there is no mention of using recycled water for direct input to any lake; the comment that such a use is the “only consideration” is incorrect.
 
The comments claim that best available planning technology has not been used, that “conclusions” (even though there are none in the Plan) are based on a conceptual model rather than on scientific method, and that an available groundwater model should be used (it is unclear what “available” groundwater model is being referenced since current groundwater modeling work is still in development and thus not yet available).  The commentors fail to recognize that a conceptual model is an essential primary step in the development of a numerical groundwater flow model, and hence a key part of what they call scientific method.  The commentors also fail to recognize that plans are not based on output or other use of a model; rather, models are useful tools in the implementation of plans.  Ultimately, the commentors fail to recognize that the Plan envisions the use of a model in analyzing various groundwater management actions before they are implemented (see Primary Plan Elements 3 and 5, and see each of the individual project descriptions in Plan’s Appendix 3).  It is worth noting that, based on re-reading some of the Plan element descriptions in preparation of this response, the discussion of planned utilization of a model in the descriptions of Plan Elements 3 and 4, and possibly 5 and 6 could be expanded; such could be done as the Plan is finalized.
 
The comments claim that “the conclusion is accepted without support that Lake Merced can be maintained in much the manner of a reservoir, ignoring its natural relationship to the aquifer” and that “this completely ignores repeated requests...that the lake be considered in conjunction with programs to restore the aquifer itself”.  The concept of “restoring” the aquifer has been raised on several occasions, all without any definition of what “restoration” might mean, or to what set of conditions might the aquifer be “restored” (although it remains somewhat obvious that the concept of “restoration” is that pumping be sufficiently curtailed for ground water to recover to some historic condition in order to hopefully increase the level of Lake Merced, regardless of the associated elimination of other beneficial uses of ground water).  As regards the current comment, the Plan includes some summary discussion and detailed references that completely belie the claim that the concept of lake maintenance is “without support”.  And several of the Plan elements, collectively, address on point the integrated management of ground water and related surface water resources (see Primary Plan Elements 2, 3, and 4).
 
In summary, as regards ground water and related surface water resources, the Groundwater Management Plan is a documentation of envisioned management efforts that will address all of the kinds of things that various interests, including the subject commentors, have been saying should be addressed in managing ground water and related surface water.
 
As to the specifically emphasized concept of injecting reclaimed water along the coastline for the purpose of retaining fresh water in the aquifer and increasing sustainable yield, an option considered to have high potential by the PUC’s Technical Advisory Committee according to the commentors, I would offer the following.  As you know, the City has recently completed, in cooperation with Daly City, the installation of a network of coastal monitoring wells that extend along the entire west coastal boundary of the basin, from Golden Gate Park to Thorton Beach.  Those wells show no evidence of seawater intrusion.  Therefore, at present, there is no identified need to inject any water along the coastline to create a barrier for the traditional purpose of coastal barriers (to control intrusion).  In the course of considering and analyzing the potential for development of ground water in the North Westside Basin (Primary Plan Element 4), the Draft Plan envisions analyzing the impacts of pumping on both coastal and inland groundwater levels (meaning simulating, with a model, the projected impacts on groundwater levels).  Fundamentally, the “project” (meaning groundwater supply wells) will be configured to avoid depression of coastal groundwater levels that would be conducive to seawater intrusion.  However, if it is determined that there is need for “mitigation” in the form of some kind of coastal barrier, then such a barrier will be considered; alternatively, less groundwater pumping will also be considered.  If a barrier is determined to be a necessary/desired coastal management tool, the logical next step would be analysis of what might constitute such a barrier, both in terms of artificial recharge facilities (vertical wells, horizontal wells, surface spreading, etc.) and sources of water (fresh or recycled).  At present, it is premature to consider injecting any kind of water, fresh or recycled, along the coastline because there is no identified need to do so.  However, in the course of considering and analyzing the potential for additional groundwater development, the potential for inducing seawater intrusion will be analyzed; and alternatives to preclude intrusion will be developed as necessary, whether they be reduced groundwater pumping or a coastal barrier.  If a coastal barrier is determined to be necessary, alternative configurations for such a barrier will be considered, where such configurations will consider both methods and sources of water.
 
Since the current comment letter adds that such an injection effort would increase the sustainable yield of the aquifer, an expansion of the preceding is appropriate.  First, since the commentors invoke the reported conclusion of a TAC that such an option would “increase sustainable yield”, it would be useful to determine what exactly was done by the TAC, and what was the basis for such injection being considered to have “high potential”?  It would be particularly useful to have the results of any analysis that supports such a claim.  The purposeful hydraulic closing of a groundwater basin to retain fresh water in order to increase sustainable yield might have an attractive ring to it but, in fact, it is a less than desirable management action on a long-term basis because it purposely entrains and concentrates salt content in the resultant closed basin.  In the manner being advanced by the current commentors, the salt issue is exacerbated by using reclaimed water to accomplish the coastal barrier because, by definition, some of the injected water needs to flow away from the barrier in both coastward and landward directions.  On top of those two issues, there is the real constraint of injecting recycled water into a potable aquifer at locations that would form a linear hydraulic ridge generally near existing and planned wells that could be used for potable water supply; by definition, recycled water would then have potential to flow toward those wells and potentially disqualify them from municipal supply due to residence time and distance requirements in the State Health and Safety Code.  It is doubtful that all of the above has been considered, analyzed, and resolved by the Technical Advisory Committee before supposedly concluding such an injection concept to have “high potential”.  Of course, if such work has been done, the results should be brought forward and considered; they would be most interesting in light of the number of issues facing such a concept.

We trust that the preceding are useful responses to the somewhat technically-related comments in the subject letter.  If we can provide further details or respond to questions regarding any of the above, we would be happy to do so.

Sincerely,

LUHDORFF AND SCALMANINI
CONSULTING ENGINEERS


Joseph C. Scalmanini

JCS/kk

Cc:    Joshua Milstein
         Anne Schneider