The Board of Supervisors this week certified a final assessment of the cumulative impacts of future development on the threatened and endangered salmonid species in the San Geronimo Valley watershed. The county has been working on the document—a supplemental environmental impact report to the 2007 countywide plan—since 2014, when the state’s first appellate court directed the county to do so in response to a lawsuit brought by the Salmon Protection and Watershed Network. Now that the board certified the document, the county is able to resume using its 2007 countywide plan to assess development projects in the San Geronimo Valley. (While preparing the E.I.R., the county had to use the 1994 countywide plan, per court order.) On Tuesday, supervisors received a report from county environmental planners and the company contracted to complete the assessment, Stillwater Sciences, before unanimously voting to certify the document. In his concluding remarks that mirrored his colleagues’ sentiments, Supervisor Damon Connolly emphasized, “I’m hoping we are reaching a point where we can spend money on actual habitat restoration and helping our salmon population, rather than on protracted litigation and expensive studies. Time will tell.” Overall, the supplemental environmental impact report found two potentially significant cumulative impacts and one less-than-significant cumulative impact to the spawning, rearing and survival of salmonids in the watershed. The first potential impact was that urbanization—or increased concrete and other impervious surfaces—will cumulatively increase stormflow magnitude and frequency, compromising the ability of rearing coho salmon to find adequate refuge during high stream flows. The second potential impact was reduced salmonid spawning success due to increased development-related fine sediment in stream channels. The last potential impact, determined to be minor enough not to require mitigation, was reduced salmonid summer rearing success due to degraded habitat conditions, including reduced habitat complexity, reduced stream flows and increased water temperature. The final S.E.I.R. commits the county to several mitigation measures, including the development and implementation of an expanded stream conservation area ordinance. (A previous version of that ordinance, approved in 2013, was put on hold due to SPAWN litigation.) In addition, the county will newly require biotechnical techniques and salmonid habitat enhancement elements for all bank stabilization projects, take new measures to reduce the production and delivery of fine sediment to streams and conduct a voluntary groundwater study. Still, in her report to supervisors, environmental planning manager Rachel Reid said, “the final S.E.I.R. will help make the environmental review process for individual development applications more efficient, because it provides program-level information and data specific to the San Geronimo Valley, which identifies potentially significant environmental impacts and associated mitigation measures that may be used in analyzing future site-specific development projects.” Although the planning commission heard many comments when they considered the document last month—primarily from valley residents who feared the assessment would unfairly lead to stricter development regulations for their homes—there wasn’t a single public comment on Tuesday. The most significant mitigation measure that will impact streamside residents is the implementation of the stream conservation ordinance. The S.E.I.R. lays out the bare bones of what the county hopes the ordinance will accomplish, including expanding the set of development activities that require a discretionary permit and site assessment. Tom Lai, the assistant director of the community development agency, said his staff anticipates bringing further details, the schedule and the budget for the ordinance as part of the systemic update to the 2007 countywide plan to the board this fall.