Abstract |
Section 303(d) of the federal Clean Water Act (CWA) and the U.S. Environmental Protection Agency's (EPA) implementing regulations direct each state to identify and list waters, known as water quality limited segments (WQLSs), in which currently required controls of a specified substance are inadequate to achieve water quality standards. For each WQLS, the State is required to either establish a Total Maximum Daily Load (TMDL) for the specified substance that the waterbody can receive without violating water quality standards, or demonstrate that water quality standards are being met. Back Creek (basin code 02-13-06-04), located in Cecil County, MD, was identified on the States list of WQLSs as impaired by nutrients (1996 listing), suspended sediments (1996 listing), arsenic (As) (1996 listing), cadmium (Cd) (1996 listing) and silver (Ag) (1996 listing). All impairments were listed for tidal waters. Code of Maryland Regulations ((COMAR) 26.08.02.03-1(B)(3)(g)) defines the Elk River, which includes the Back Creek tributary, as a fresh waterbody. The information used for listing Ag, As, and Cd was obtained from an 1989 study that is suspect due in part to sampling and analysis methods available at the time, and assessment inconsistencies that led to the listing in 1996. This will require the State to perform additional studies in this area to identify the contaminant(s) responsible for causing the observed sediment toxicity. |