Clear Creek Solutions conducted an update of the wetland calibration criteria in WWHM 2012 model. CCS added additional analysis tools and created algorithm for determining pass/fail relationship of flow event.

Wetland volume analysis using the standard criteria set #1 and #2 that are outlined in the WSDOE SWMM (Washington State Department of Ecology Stormwater Management Manual) has proven to be inadequate for developers in the region and has made many projects unfeasible. Development of additional criteria has been suggested to make projects feasible and achievable for developers and jurisdictions alike. When referring to new criteria sets in this report, CCS is referring to the 4 new kinds of criteria that may be added to the existing criteria in the SWMM. Criteria #1 described in this report has no association with criteria #1 in the SWMM and is simply a numbering system for the new criteria options being evaluated.

ECOLOGY in coordination with Clear Creek Solutions has updated Method 2: Wetland Criteria for determining volumes and impactful depth excursions for wetlands.