PNW 98 Session - Full Abstracts

Full Abstract

Amanda Azous (1)
Mason Bowles (2)
Klaus Richter (3)

(1) Azous Environmental Consulting , Olga, WA 98279-0530
(2) King County Dept. of Development and Environmental Services, Renton, WA 98055-1219
(3) King County Department of Natural Resources, Seattle, WA 98104

Empirically Derived Standards For Wetland Mitigation
or
Mitigation Meets The Real World

Reference standards for planning and designing the creation, restoration, and enhancement of functions associated with depressional flow-through wetlands were developed based on data from surveying 19 Puget Lowland wetlands. The reference standards were used as a basis for project level standards developed as benchmarks of performance against which the ecological characteristics associated with specific wetland functions can be measured. These reference and performance standards are based on a hydrogeomorphic approach to wetland characterization and assessment. The standards were empirically derived and represent the range of values (i.e., highest to lowest) for different ecological variables determined from surveys of reference wetlands. A major finding is the complexity of actual wetlands as compared to common expectations of mitigation projects.

We derived both the reference and project performance standards from the analysis of long-term field studies of 19 (reference) wetlands in the Puget Sound Lowlands, special studies of six wetlands, four of which were heavily impacted by urbanization and some additional surveys of four wetlands in order to analyze snags and woody debris in wetlands and buffers and wetland topography.

The reference and performance standards primarily address habitat conditions and provide a model for assessing birds, mammals, amphibians, general habitat and plant community conditions. These measurable benchmarks were developed to be used as a standard of comparison, against which measurements of mitigation project characteristics can be evaluated. Project monitoring data can be evaluated against project performance standards as well as project objectives and goals to determine a project’s success or failure.