Abstract |
Section 303(d) of the federal Clean Water Act (CWA) and the U.S. Environmental Protection Agencys (USEPA) implementing regulations direct each state to identify and list waters, known as water quality limited segments (WQLSs), in which current required controls of a specified substance are inadequate to achieve water quality standards. A water quality standard is the combination of a designated use for a particular body of water and the water quality criteria designed to protect that use. For each WQLS listed on the Integrated Report of Surface Water Quality in Maryland (Integrated Report), the State is to either establish a Total Maximum Daily Load (TMDL) of the specified substance that the waterbody can receive without violating water quality standards, or demonstrate via a Water Quality Analysis (WQA) that water quality standards are being met. The Cabin John Creek watershed (basin number 02-14-02-07), located in Montgomery County, was identified on the Integrated Report under Category 5 as impaired by nutrients, suspended sediments (1996 listings), fecal bacteria (2002 listing) and evidence of impacts to biological communities (2006 listing). All impairments are listed for nontidal streams. The 1996 nutrients listing was refined in the 2008 Integrated Report and phosphorus was identified as the specific impairing substance. Similarly, the 1996 suspended sediment listing was refined in the 2008 Integrated Report to a listing for total suspended solids. A TMDL was completed for the Cabin John Creek watershed for fecal bacteria in 2008. |