Performance Evaluation of Nonpoint Source BMP Tracking Systems

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HydroAnalysis worked with stakeholders to design a system to quantitatively track nonpoint source (NPS) nitrogen reductions throughout the five-state Long Island Sound (LIS) watershed area. The evaluation tracked progress in reducing NPS nitrogen loads throughout the LIS watershed, as required by the Long Island Sound nitrogen TMDL. We assessed needs for the system to track NPS control measures, reviewed available tracking systems, and implemented a screening process to match potentially suitable tracking systems with LIS needs. NPS control measures include two types of measures: 1) mitigation measures which embrace a wide range of urban stormwater and agricultural best management practices (BMPs), and 2) management activities, such as street sweeping and agricultural tilling practices. As a result, NPS control measures represent a wide range of activities and programs that result in control or reduction of pollutant loadings.

HydroAnalysis conducted research, prepared technical memos that were accessible to a public audience, conducted stakeholder meetings and webinars, listened to stakeholder inputs, and identified suitable tracking systems. We conducted the project collaboratively, working closely with staff from five state agencies, US EPA, and environmental advocacy groups. The HydroAnalysis evaluation was successful in selecting a custom-designed quantitative tracking system to support long-term evaluation of the NPS and stormwater nitrogen reductions required as part of the LIS TMDL implementation plan. The selected and stakeholder-approved NPS nitrogen reduction tracking system for the LIS watershed was sufficiently robust to support the TMDL implementation process, watershed planning, and cost-benefit analyses.

This project was conducted for the New England Interstate Water Pollution Control Commission and the Long Island Sound Study Program through the WaterVision joint venture.