Crissy Field, Presidio, San Francisco, CA

The Presidio in San Francisco had a heavily contaminated airfield when it was abandoned by the military and was acquired by the National Park Service. After removal of the airfield and a major remediation of its contamination, the Park Service recreated a historical tidal lagoon at the scenic airfield site that opened to the public in 1999.

The objectives of the re-design of the airfield were many, and included both high public use and restoration of ecologically functioning tidal wetlands. The project had both public and private funding, and lots of public attention. Fundamentally, the project is a huge public success, in spite of serious hydrological problems and questionable ecological success.

The privately-produced 2003 and 2004 technical reports provided by Katie on the blog are the primary source of my information about the project's goals and relative successes and failures; a search for peer-reviewed literature that could add more current information about the project was not successful.

The project's hydrology problems are complex. Since the completion of the "restoration" (at about 20 acres it represents a tiny portion of the infilled historic lagoon), there have been insufficient flows both in and out of the lagoon; heavy scouring by seasonally strong flows and the deposition of new sand has substantially changed its morphology over a short period of time; it appears to be too deep to support a complex range of plant species; banks are too steep in many places, and bank erosion is a problem; freshwater inlets have changed from their historic flows and flow locations due to upland construction and landform changes, and now carry additional piped-in stormwater (this freshwater information comes from personal research). The hydrology reports recommended re-engineering the morphology of the lagoon in order to correct its function, and specifically recommended a major enlargement of the lagoon.

The overall ecology of the lagoon was less directly addressed in these reports, but recommendations for adaptive monitoring revealed that the original ecological models and goals were insufficiently specific and clear. The re-creation of a generally historic model of the original lagoon seems to have been the original goal, with species richness and eradication of invasive species as primary targets. But the engineered lagoon does not replicate the size, location, hydrology, or function of the long disappeared lagoon, and the current condition of its small model seems to have so far failed to meet even general goals. More to the point, it is clearly problematic to assess the success of a project when goals are overly broad, when there is no specific reference model, and when benchmark measurements for success are not devised.

Compared to these ecological goals, the social goals for the project appear to have been very clear, and to be clearly successful. The park, which provides access to the bay's edge near Golden Gate, is well-loved and well-used, and a formerly blighted area provides healthy outdoor recreation to a large local population. There may be hidden social issues in regard to park management, of course, but this project did not suffer from disregard for the space as a public amenity. It anything, the public use dominated the attention of the planners to the detriment of ecological services for non-human species.

photo GGNRA web site

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