Assessing the Effectiveness of Land Use Regulations in Developing, Rural King County, WA

Land use regulations are commonly established to avoid or minimize and mitigate the biophysical effects of development, yet their effectiveness is rarely assessed. We present a framework for assessing regulatory effectiveness, taking advantage of a relatively new set of land use regulations started in 2005 by King County to protect critical areas, including fish-bearing aquatic areas, as directed by the Washington State Growth Management Act (GMA). The new regulations were controversial in part because effectiveness of previous regulations was unknown.  To remedy that knowledge deficit and to provide science-based information for a 2012 GMA-required regulatory review by the King County Council, we initiated a five year study to assess whether the new set of regulations are preventing development related environmental change. We hypothesize that if regulations are ineffective, then the direction and magnitude of change over time in select environmental response variables should differ among watersheds subject to development (treatment) and no development (control). Furthermore, if change is observed it should be commensurate with the type, direction and magnitude of change over time in land covers and land uses.

A real-time, treatment-control experiment was established using nine small (80 to 1,200 ha) fish-bearing, glacial till-based, low-elevation watersheds, comprised of six treatment and three controls, wherein changes in land cover and land use and concomitant changes in stream flows, benthic invertebrates, conductivity and habitat complexity are assessed. Relatively small streams and watersheds were selected for assessment because they are known to be responsive to development and  for tractability in documenting land use and environmental response. Similarly, we selected hydrology based parameters for assessment because development affects fundamental water dynamics and chemical properties.  Relative to many historic efforts at evaluating effectiveness, the study design is strengthened by several key elements including: 1) tracking changes over time rather than substituting space for time, 2) assessing historic changes in land covers, to better understand initial environmental condition and future trajectories and innovative techniques for 3) assessing channel morphology changes using tracer technology and 4) quantifying land cover changes using a spatially-explicit model and distance-weighted measures of land covers and 3) a Bayesian probabilistic approach to interpreting results to complement standard statistical methods.