Best Available Science

11 months ago

The Growth Management Act (RCW 36.70A) requires Washington’s counties and cities to review, evaluate, and update comprehensive land use plans, as well as updating development regulations using Best Available Science (BAS) to identify, designate and protect critical areas.

Mercer Island last updated its Critical Area regulations in 2005, and an update is due by summer, 2019. The City hired a consultant, ESA, to conduct an analysis of the Best Available Science as it pertains to the critical areas located in Mercer Island. ESA's findings are available in two reports here and here.

Mercer Island is home to 5 types of critical areas:

  1. Wetlands
  2. Watercourses
  3. Fish and wildlife habitat conservation areas
  4. Geologically hazardous areas
  5. Critical aquifer recharge areas
ESA analyzed scientific research pertaining to the protection of these 5 types of critical areas and performed a gap analysis of the BAS findings and Mercer Island's current critical area regulations. At a high level, the BAS shows that the City should expand buffers around critical areas (buffers are a setback area around the critical area where development activities are restricted). The Planning Commission has been briefed on these findings and is considering the BAS as they develop draft code language.