Using plan and ordinance quality to evaluate the implementation of riparian buffer policies

Abstract

Comprehensive plans, development management ordinances, and approved development applications help shape the landscape features that affect water resources. The translation of a plan and ordinances into action, however, cannot be assumed. This paper examines riparian buffers, a prominent stormwater control measure. The central research question is: Does the quality of policy inputs help explain the amount of tree cover and impervious surface within riparian buffers? Data come from a cross-sectional study of 178 development applications sampled from 14 jurisdictions in two watersheds in North Carolina and Maryland. Research methods include 1) the content analysis of policy inputs including plans, ordinances, and development applications, 2) tree cover and impervious surface calculations within riparian buffers using 1 m high-resolution land classification maps, and 3) logistic regressions to test the relationships among these variables and community and site-specific variables. The likelihood of a buffer contained 75% or more tree cover increased with higher plan and ordinance quality scores and decreased for developments with more lots. The likelihood of a development’s buffer contained 5% or more impervious surface increased with higher growth rate, higher population density, and in developments containing more lots. Results suggest jurisdictions could include more of the goals, fact base, and policies the water resource protection literature associate with watershed protection and optimal riparian buffer functioning. Findings could also inform outreach during the permitting process and help practitioners create monitoring and restoration programs targeted at developments where impervious surface encroachment is more likely to occur.