Regional monitoring network being built to evaluate BMP performance

Posted January 29, 2021
A bioswale that runs along the side of a roadway in Orange County collects and treats stormwater runoff. The Southern California Stormwater Monitoring Coalition (SMC) has begun building a regional monitoring network to track the performance of a wide variety of bioswales and other stormwater BMPs.

The Southern California Stormwater Monitoring Coalition (SMC) has begun building a regional monitoring network for tracking the performance of a wide variety of stormwater BMPs (best management practices) – a critical step toward being able to optimize the long-term effectiveness of these water-quality control measures.

The three-year initiative, launched in December and led by SCCWRP, will develop a regional BMP monitoring program that stormwater managers across coastal Southern California can use to rapidly collect high-quality, comparable data sets on the field performance of structural BMPs. Structural BMPs are a ubiquitous class of engineered field solutions – everything from vegetated swales to permeable pavement – that are implemented to improve runoff water quality.

The SMC’s Regional BMP Monitoring Network, expected to be operational by 2023, will help address significant, persistent knowledge gaps in managers’ and BMP designers’ regional understanding of structural BMP performance.

In recent years, structural BMPs have been implemented at an increasingly rapid pace across heavily populated Southern California to improve and protect the health of watersheds.

Although Southern California managers are now spending tens of millions of dollars every year to implement stormwater BMPs, they have largely lacked the monitoring tools and infrastructure necessary to meaningfully evaluate the long-term performance effectiveness of structural BMPs – and to compare performance across the many individual jurisdictions that have implemented BMPs.

Most BMP implementation decisions to date in Southern California have been made based on limited performance effectiveness data and analyses – often from outside the region – even as researchers know that local conditions can dramatically affect how well structural BMPs perform. In particular, Southern California’s relatively short but intense rain events affect BMP performance, as do the major types and levels of pollutants being treated.

SCCWRP will develop a scientifically robust monitoring design for the SMC’s Regional BMP Monitoring Network, enabling BMP designers, planners and managers across Southern California to use consistent, standardized methods for collecting and analyzing field data on existing structural BMPs. The network will boost management confidence in BMP performance effectiveness analyses and in the applicability of findings to all stormwater managers regionally.

In particular, the network will help BMP designers, planners and managers determine which BMPs work best for each pollutant, how BMP designs can be improved to enhance pollutant reductions, and what maintenance should be used to ensure each BMP operates at maximum efficiency throughout its lifespan.

The program’s data also will be used to improve tools like the California BMP Effectiveness Calculator, a SCCWRP-developed management tool for estimating the effectiveness of BMPs in removing specific types of contaminants from runoff.

The core value of the integrated, coordinated regional monitoring effort is that SMC member agencies and other participants will be able to collect much more BMP performance data at a fraction of the effort than if they collected the data on its own. Already, 20 stormwater management agencies are signed up to serve on the project’s technical working group and will be partners in building the network.

Once built, the network is expected to become the largest of its kind in the nation – a necessity in Southern California where opportunities to collect BMP performance data are limited by the region’s relatively infrequent rain events.

For more information, or to become part of the Regional BMP Monitoring Network, contact Dr. Elizabeth Fassman-Beck.


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