The City of Kirkland Public Works Department was interested
in developing an Advanced Mitigation Project to allow for faster and more seamless
permitting for future City infrastructure projects that require wetland and/or
stream buffer mitigation. The Watershed Company provided the City with an assessment
of viable city-owned properties in order to select sites at which restoration
activities were feasible and could provide sufficient functional lift. The City
provided a list of 21 potential restoration locations Watershed conducted
inspections at each site and mapped suitable wetland and/or buffer enhancement
areas. Each site was then quantitatively scored according to an 11-parameter
framework that Watershed developed specific to this project. Potential site
attributes included size; the extent and quality of existing native vegetation;
the extent and composition of non-native, invasive vegetation; proximity to
wetlands and salmon-bearing streams; potential for functional lift;
construction access/feasibility; existing soil condition/compaction;
limitations on vegetation due to utilities, contamination, or height
restrictions. The relative scores for each site were tabulated, and the sites
were then organized into a four-tier ranking and provided to the City with the
accompanying GPS-based maps and costs estimates for installation, maintenance,
monitoring, and long-term stewardship. Based on this analysis the City selected
the preferred alternative, an expansive, reed canarygrass-dominated wetland
associated with Forbes Creek.
Once the preferred alternative was selected, Watershed
developed a restoration plan unique to each site. Given the extent of
reed canarygrass presence and highly fluctuating water levels, Watershed relied
on adaptive design techniques that had proven effective previous restoration
designs we had developed in similar environments. We continued to provide oversight
of all construction activities during project installation and are in the
process of completing the as-built inspection to document substantial
completion of the mitigation installation. Watershed will be providing annual
performance monitoring to ensure the site meets all of its associated goals and
performance standards. Once complete, the advanced mitigation will provide
approximately 2.4 acres of wetland and buffer enhancement that the Public Works
Department can use as credits for future wetland and stream buffer impacts at a
1:1 ratio.
