Developing a Stormwater Post-Construction Ordinance that will Protect Mecklenburg County's Watersheds

Mecklenburg County, the City of Charlotte, and the towns of Cornelius, Davidson, Huntersville, Matthews, Mint Hill and Pineville are working jointly to develop ordinance provisions that control and manage stormwater runoff to meet the state and federal NPDES Phase II stormwater post-construction requirements and additional watershed protection objectives. Charlotte Storm Water Services and the Mecklenburg County Water Quality Program are implementing a multi-phased approach to build public support and lead to the adoption of ordinances by early 2006. These partners have engaged a diverse committee of stakeholders in reviewing watershed modeling results, developing and evaluating alternative management approaches, and in crafting ordinance language. The overall objective of Phase 1 of the project was to establish the technical basis for ordinance development and build modeling and costing tools to evaluate proposed management alternatives under later phases of the project. The primary objective for Phase 2 was to facilitate discussion among stakeholders and municipal staff to develop and evaluate alternative management scenarios to address the gaps identified by the baseline analysis. The environmental indicator and costing models were to be used to predict outcomes and provide the technical basis for comparison of alternatives. Input was obtained from stakeholders to compare other criteria including compatibility with other community values, political feasibility, and administrative feasibility. The objective for Phase 3 is to translate the consensus management scenario produced during Phase 2 into specific ordinance language, provide for public review, and adopt final versions among the partner municipalities by early 2006.Hydrologic and pollutant loading modeling frameworks were developed and linked to a land use database established for approximately 2600 subwatersheds. Future land use projections were compiled from more than twenty planning area master plans and based on input from each municipality's planning staff. Expectations for changed land use and imperviousness were summarized for all 33 named watersheds. Impacts were summarized for several key indicators including sediment load, phosphorus and nitrogen loads, and stream channel instability risk. Site evaluation tools were used to analyze the changes to runoff, pollutant load, and cost for each land development type from applying different BMPs reflecting management options proposed by stakeholders for ordinance consideration. Results were then aggregated to the watershed scale for large-scale comparison.The modeling analyses were critical to obtaining public support for ordinance revisions. The effort provided a strong technical basis to explain to a diverse group of stakeholders why changes are needed and the environmental consequences of not taking action. Linking watershed indicators to stakeholder goals and objectives engaged stakeholders and provided the basis for objectively evaluating management alternatives. The process helped leverage stakeholder factions off of extreme positions by demonstrating how certain compromises would help meet the overall goals and objectives. Stakeholders became better informed, and the county and its municipal partners have made great strides toward a countywide, comprehensive, watershed-based post-construction stormwater control program that meets regulations and other local objectives.