The Effectiveness of Land Use Regulations in Protecting Habitat in Rural King County, Washington

King County’s land use regulations were assessed for compliance and effectiveness at protecting hydrology in developing rural areas. From 2008 to 2012, permit activity and changes in land cover, hydrology, water quality, channel complexity and biology were assessed among nine small (80 to 1400 ha) study watersheds with salmonid-bearing streams in a before-after/control-impact (BACI) design comprised of six “treatment” watersheds with active, ongoing development and three “reference” watersheds with no development and near-complete forest cover. Historic (ca 1910, 1936, 1947, and 1965), potential full build-out, and urban land cover scenarios were developed and modeled. No significant environmental response was detected but development was low, probably due to “The Great Recession”.  Low rates of observed and predicted change, good compliance in buffers, and modeled findings suggest that the County’s regulations may be protective of watershed-scale hydrology and regulatory buffers. This study provides new insight on regulations and improved confidence that physical improvements to stream channel and riparian habitats may not be undone by a development-driven change in watershed hydrology or regulatory noncompliance. The study provides a basis and hypothesis for future monitoring and a framework to assess effectiveness of habitat restoration in small streams of the Puget Lowland Ecoregion.