County releases final SEIR on development


Court mandates from a lawsuit won by the Salmon Protection and Watershed Network in 2012 have until now barred the county from using the most recent development standards for the San Geronimo Valley—pending an analysis of cumulative development impacts on fish.

Last week, after a lengthy delay, the county addressed that order with the release of the final supplemental environmental impact report that corresponds to the 2007 Countywide Plan.

Until now, the county relied on an outdated Countywide Plan—an enormous planning document that guides policies and programs, including to minimize adverse development impacts on biological resources—from 1994 when it assessed the impacts of new and expanded development in the valley.

In June, the county bumped up the funds allocated to the company contracted to complete the final environmental document, Stillwater Sciences, by $20,000 for a total of $279,106.

The county expected to release the final document much earlier, but said it was delayed “due to the large number and complexity of comment letters received.”

The final report, which will be reviewed by the Planning Commission in September before it heads to the Board of Supervisors for certification, makes a series of determinations. 

It states the effects of urbanization—and specifically of increased concrete and other impervious surfaces—will cumulatively increase stormflow magnitude and frequency. Those changes will compromise the ability of rearing coho salmon to find adequate refuge during high flows. The report also shows reduced salmonid spawning success due to increased development-related fine sediment in stream channels.

In response to the findings, the report proposed expanding and strengthening a stream conservation area ordinance—which was also on hold for the past decade due to the litigation—that regulates development, controlling and reducing the production and delivery of fine sediment to streams, and a number of winter habitat enhancement projects.

A third impact was determined to be minor enough not to require mitigation: reduced salmonid summer rearing success due to degraded habitat conditions, including reduced habitat complexity, reduced streamflow and increased water temperature.

While not required, the county elected to pursue a number of voluntary mitigation measures to address this, according to the report. Those measures include a groundwater study to determine how development might adversely impact the summer base flow in San Geronimo Creek as well as additional stream enhancement projects specific to the summertime.

Adequate cumulative impacts reporting and mitigation strategies were the two holes that SPAWN identified in the county’s 2007 environmental impact report for the Countywide Plan.

The final document also includes a section that specifically addresses a number of common concerns expressed during the public scoping period on the draft, which was released last April. 

Answering a question about the scope of cumulative impacts, the document clarifies that the analysis of cumulative impacts not only focuses on future residential development but also considers historical damming and diversions, forest-clearing and overfishing.

There were also concerns submitted about information sourcing. The document states that it used past and ongoing reports from the Marin Municipal Water District, the National Marine Fisheries Service, Prunuske Chatham, Inc. and Stillwater Sciences. The report analyzes current conditions and stressors for individual salmonid life stages, but due to limited information, does not examine juvenile migration or adult migration stages.

Nor does it analyze ecological interactions like competition between salmonid species, as some commenters had wished. 

In describing an expanded stream conservation area ordinance, the document states that ordinance will impose additions and amendments to county development code. For instance, proposed development that has the potential to adversely impact salmonids would newly require site plan review. 

Implementation of the new standards, however, is expected to take up to five years from the date that the current—and any threatened—litigation is resolved. 

Todd Steiner, executive director of SPAWN’s umbrella organization Turtle Island Restoration Network, said he had not yet reviewed the final document. (The organization submitted 30 pages of comments to the draft report.)

If the Board of Supervisors certifies the document, County Counsel Brian Washington said the county will then file a return to the court to show they have fulfilled the order. SPAWN will then have 30 days to bring further litigation. 


The Planning Commission will consider the final supplemental E.I.R. on Sept. 24. You can find the document, which includes responses to public comments, on the Marin County website under the Community Development Agency under “environmental review” and “2007 Marin Countywide Plan Supplemental E.I.R.”