Researchers sampled for microbial contaminants in effluent from the
stormwater treatment systems evaluated in this three-year study.
Designed to mimic natural stream channels, swales are the most common approach to stormwater management in the world. In this study, however, they were not high water quality performers.
Weathering the Storm
Study reveals that when it comes to managing stormwater to protect water quality, it’s time to challenge conventional wisdom.
Challenge
Stormwater carrying nonpoint source pollution is the greatest threat to water quality nationwide. It’s also a focus of Phase II of the Clean Water Act, which mandates communities with populations smaller than 100,000, to develop stormwater management programs to improve water quality and reduce the volume of runoff. To create such programs, there is no lack of stormwater treatments from which to choose. The challenge is to identify an approach that will do the best job of protecting local water quality. However, independent, scientifically-verified information about the effectiveness of different approaches is lacking.
Response
CICEET-sponsored researchers
at the University of New Hampshire designed a three-year study to evaluate the effectiveness of 10 different
stormwater treatment systems in N.H.’s Great Bay Estuary watershed. Five of the treatments were wet systems, five were dry, and some had swales or vegetated
strips incorporated into the design.
The researchers combined intensive hydrologic monitoring with periodic sampling of common stormwater pollutants, including microbial indicators such as Escherichia coli, nutrients, oil, grease, and heavy metals. Sampling took place during, and between, storm events. Data revealed that while wet systems were slightly more effective at pollutant removal, this effectiveness varied depending on the contaminant. In nearly half of the cases, the stormwater treatments actually degraded water quality. Several commonly-used approaches—including some Best Management Practices—were not effective in removing contaminants. variables.
Impact
This study served as a springboard to a research and outreach initiative that is dedicated to the protection of water resources through effective stormwater management. The CICEET-sponsored University of New Hampshire Stormwater Center evaluates the effectiveness of different stormwater treatments in a side-by-side setting, under strictly controlled conditions. The assembly of stormwater treatments at this field site makes it an ideal setting for research, workshops, technology demonstrations, and mini-courses.
Learn More
Dr. Tom Ballestero
Principal Investigator, UNH Stormwater Center
603.862.1405
tom.ballestero@unh.edu
Dr. Robert Roseen
Director, UNH Stormwater Center
603.862.4024
robert.roseen@unh.edu