Final TMDLs Approved by EPA: Tuckahoe Lake

Tuckahoe Lake is an impoundment located near Ridgely in southwestern Caroline County, Maryland.  The impoundment, which is owned by the Maryland Department of Natural Resources (DNR), lies in the Choptank River watershed.  A dam was constructed in 1975.  Upstream watershed usages include Tuckahoe State Park and fish stocking (including largemouth bass and tiger muskie).  Downstream watershed usage includes Tuckahoe State Park.  The inflow to Tuckahoe Lake is primarily via Tuckahoe Creek. 

Based on mercury data in fish tissue from a subset of lakes across the State, the Maryland Department of Environment (MDE) announced a statewide fish consumption advisory for lakes this year.  This advisory has been established statewide as a precautionary measure because the primary source of mercury is understood to be atmospheric deposition, which is widely dispersed.  Based on additional fish tissue data,Maryland has verified that Tuckahoe Lake is impaired due to mercury in fish tissue. 

Section 303(d) of the federal CWA and EPA’s implementing regulations direct each state to identify and list waters, known as water quality limited segments (WQLSs), in which current required controls of a specific substance are inadequate to achieve water quality standards. The CWA requires the development of a Total Maximum Daily Load (TMDL) for all impaired waters on their Section 303(d) list.  A TMDL reflects the maximum pollutant loading of an impairing substance a waterbody can receive and still meet water quality standards.  A TMDL can be expressed in mass per time, toxicity or any other appropriate measure (40CFR 130.2(i)).  A TMDL must take into account seasonal variations, critical conditions and a margin of safety (MOS), to allow for uncertainty.  Maryland’s 2002 proposed 303(d) list prepared by MDE lists Tuckahoe Lake as impaired for mercury in fish tissue. This TMDL was developed in response to the determination of impairment.   

TMDL of Mercury for Tuckahoe Lake, Caroline County, Maryland

(Approved on January 27, 2004)

EPA's Decision Letter

EPA's Decision Letter

Main Report


Comment Response Document


Contact Information

Please direct questions or comments concerning this project to Maryland's TMDL Program at (410) 537-3818.