Incorporating Impervious Cover Into Water Quality Plans
STORMWATER CONTROL | WHAT IS IMPERVIOUS COVER?
A new strategy for developing pollution control goals for highly urbanized areas.
By: Chester Arnold, Kelly Collins, Deb Caraco, Anne Kitchell, and Lori Lilly, Public Works , March 2011
In February 2007, the U.S. EPA entered the next generation of watershed-based pollution control by issuing a Total Maximum Daily Load (TMDL) based not on a specific pollutant but on impervious cover. The goals for Connecticut’s 2.4-squaremile Eagleville Brook Watershed integrate aspects of urban development. Since then, similar TMDLs have been or are being developed across the Northeast, including in Maine, Massachusetts, and North Carolina. In Connecticut, 238 square miles of impervious cover (about 5% of the state) was added between 1985 and 2006. This work is expected
to become a national model by which communities can use a framework of impervious cover management to meeting water quality goals. Typically, TMDLs are managed by local jurisdictions through a waste load allocation established by the state. In this case, the Connecticut Department
of Environmental Protection (DEP) determined that a biological impairment — such as low fish densities in some areas and large amounts of aquatic habitat completely unoccupied in others — existed, but couldn’t be attributed to one specific pollutant. Instead, the impairment was attributed to an array of pollutants transported by stormwater and linked to urbanization, and — more directly
— impervious cover. Read more…
