Abstract |
Chlordane, a pesticide no longer authorized for use in the United States, has been detected in certain Back River fish tissues at levels that required the issuance of a consumption advisory. This advisory has been in place since February 5, 1986. As a consequence of this impairment by chlordane, Back River was identified as a water quality limited segment on the 1996 Section 303(d) list. This document establishes a TMDL of 0.00059 ug/L in the water column based on the United States Environmental Protection Agency water quality criterion for chlordane and the U.S. Food and Drug Administration guidance level of 0.3 mg/kg in fish tissue. Since the TMDL value is impracticable to monitor directly in the water column, the U.S. FDA guidance level will serve as the targeted endpoint. In the absence of any defined current sources of chlordane other than sporadic low levels from urban runoff sources, there is no opportunity to allocate loadings among point and non-point sources. The State intends to periodically monitor the contaminant levels of fish and sediments in Back River to track the expected gradual declines, which are indicated in currently available sediment data. The goal of the monitoring program will be to identify fish tissue levels that would allow for the withdrawal of the fish consumption advisory. |