Critical Areas Mitigation Site Monitoring Services

  • Zackuse Creek mitigation site Year 3 monitoring
  • East Lake Sammamish Trail project Year 3 monitoring

King County Department of Natural Resources and Parks (DNRP) has constructed multiple critical areas mitigation sites as required by the local jurisdictional code to offset impacts from DNRP projects across King County. Confluence managed consecutive contracts from 2015-2020 to perform post-construction mitigation site monitoring and reporting for numerous such mitigation sites. Monitoring efforts typically included creating as-built reports, conducting quarterly site inspections, providing quarterly recommendations of maintenance needs, and conducting annual monitoring events. For all projects, Confluence’s involvement aided DNRP in understanding and meeting the mitigation reporting requirements imposed on the project by various local jurisdiction’s permits within the allotted timeframe.


The annual monitoring included quarterly site inspections to evaluate and document maintenance needs, and fall (and sometimes spring) monitoring and reporting to evaluate the performance of the mitigation site compared to the established performance criteria. Typical performance criteria included plant survival, percent cover of native and invasive species, and presence of functional wildlife habitat features. Mitigation site assessment methods typically included conducting plant census, continuous line intercept transects, vegetation plot quadrats, visual inspections, and photo-point documentation to compare plant growth year to year. To improve monitoring efficiencies, Confluence created several custom monitoring templates that allow for rapid assessment of each site. The quarterly site inspections provided DNRP with guidance necessary for site maintenance and upkeep between annual monitoring events. Mitigation monitoring field effort results were documented in detailed reports that satisfy the monitoring report requirements of local jurisdiction’s code. Confluence typically closed mitigation site monitoring as soon as the site met all performance standards.


Confluence successfully guided 5 of the DNRP mitigation projects to completion before end of the contract. Through advising maintenance efforts and documenting site progress, Confluence ensured the long-term success of these mitigation sites to the satisfaction of the mitigation plan permit requirements.

Project Location
King County-Wide

King County Department of Natural Resources and Parks

Project Timeline
2015 – 2020