Program Effectiveness Assessment and Improvement Plan Tracking, Quantifying, and Reporting for Phase II MS4 Permit Compliance
The 2013 California Phase II General MS4 Permit (MS4 Permit) specifically requires a Program Effectiveness Assessment and Improvement Plan (PEAIP) to include “quantification of pollutant loads and pollutant load reductions achieved by the program as a whole” (Section E.14.a.ii.a.6) and to “quantitatively assess BMP performance at reducing pollutant loads wherever feasible, using … science-based estimates of pollutant load removal for BMPs where direct measurement of pollutant removal is overly challenging” (Sections E.14.a.ii.d.2 and E.14.a.ii.b.4). Additionally, the PEAIP requirements include using “receiving water monitoring to identify priority areas for program improvement” (Sections E.14.b.i)
To address these requirements, the County of Santa Barbara, and the Cities of Buellton, Solvang, Goleta, and Carpinteria (jurisdictions), along with Geosyntec Consultants (Geosyntec), developed a baseline pollutant load quantification, catchment prioritization, and BMP reduction model (LPRM). LPRM is accessible from an easy to use Excel interface and consists of five main components: 1) calculating the MS4 Permit Area and watershed baseline wet weather annual average pollutant load/runoff volume; 2) prioritizing catchments for program improvements; 3) tracking BMP implementation details (e.g., type of BMP implemented, catchment(s) implemented on, applicable land uses, etc.); 4) estimating the BMP pollutant load/runoff volume reductions; and 5) summarizing and formatting all results for easy reporting.
In this presentation we will describe the development of LPRM and difficulties that we overcame in the process, including calculating and calibrating catchment based pollutant loading for 12 parameters, creating a comprehensive approach to identify priority areas based on local monitoring data and jurisdictions pollutant priorities, determining BMP reduction estimates applicable to future redevelopment projects, accounting for multiple BMPs that potentially treat the same area, and building the capacity to simply update the watershed GIS data or add new BMPs, revised land use EMCs, or new pollutants as additional data becomes available. Then we will demonstrate how LPRM is being implemented within the jurisdictions to successfully and succinctly fulfill the MS4 permit requirements. Finally we will provide practical examples of how LPRM and the associated technology could be applied in a variety of watershed management scenarios directly applicable to the audience, including 1) providing real-time watershed estimates of the groundwater recharge occurring from BMP infiltration; 2) meeting watershed planning requirements necessary for state grant eligibility; 3) forecasting long-term BMP implementation needs and costs to meet TMDL Waste Load Allocations (WLAs); and 4) identifying and prioritizing potential structural BMP retrofit opportunity sites.
Using LPRM has allowed the jurisdictions to adaptively manage their ongoing BMP implementation while quantitatively assessing BMP performance and identifying priority areas, thus fulfilling key requirements of the MS4 permit through the end of this cycle and preparing them for successful stormwater management under the future permit.