Water Quality Analyses (WQA) with EPA Concurrence of MDE's Findings: Prettyboy Reservoir

Prettyboy Reservoir is an impoundment located near Beckleysville and Hereford in Northwestern Baltimore County, Maryland.  The impoundment is owned by the Baltimore City Department of Public Works and is situated in the Gunpowder River watershed.  Upstream watershed usages include an unnamed park surrounding the reservoir, fishing, boat launching facilities and fish stocking.  Downstream watershed usage includes a water supply to the City of Baltimore via Loch Raven Reservoir.  The inflow to Prettyboy Reservoir is primarily via the Gunpowder River. 

The Prettyboy Reservoir (basin code 02130806) was first identified on the 1996 303(d) list submitted to EPA by the Maryland Department of the Environment (MDE) as impaired by heavy metals and nutrients, with fecal coliform, methylmercury and biological impairments added to the list in 2002.  The heavy metal, nutrient, and methylmercury impairments were listed for the impoundment and the fecal coliform and biological impairments were listed for the non-tidal streams.  The initial listing for heavy metals was questionable because:  1) no specific pollutants were defined; 2) the original listing was based on total recoverable metals (current standard is based on dissolved metals); 3) inappropriate sampling techniques were applied (lack of filtration); 4) supporting data needed to interpret criteria was not available (hardness); and 5) a default hardness of 100 mg/l was used to convert and relate the total recoverable metals to the dissolved criteria, which superceded the total recoverable metals criteria. A water quality analysis (WQA) of heavy metals for the Prettyboy Reservoir impoundment was performed using recent water column and sediment toxicity data.  Results show no impairment for heavy metals.  The non-tidal streams are not listed for heavy metals therefore they are not addressed in the WQA.  A TMDL for methylmercury in fish tissue was completed in 2002.  A nutrient TMDL was completed in 2006. The fecal coliform and biological impairments will be addressed separately at a future date.

WQA of Heavy Metals for the Prettyboy Reservoir Impoundment, Baltimore County, MD

(Concurrence November 10, 2003)

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.