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

Piney Run Reservoir is an impoundment located near Eldersburg in Carroll County, Maryland.  The impoundment, which is owned by Carroll County, lies on Piney Run, a tributary of the South Branch Patapsco River.

Piney Run Reservoir in the South Branch Patapsco River watershed (02130908) was identified on Maryland’s 1998 list of WQLSs as being impaired by nutrients and sediments.   The sediment impairment was addressed in the “Water Quality Analysis of Sedimentation for Piney Run Reservoir in Carroll County, Maryland,” approved by EPA in November 2003.  The current  report provides an analysis of recent nutrient-related monitoring data, which show that water quality parameters associated with nutrients fall within the State’s standards at the present time.  Piney Run Reservoir thus currently meets its designated use.  However, the reservoir is borderline between mesotrophic and eutrophic status with respect to nutrient supply, biological productivity, water clarity, and oxygen depletion in the hypolimnion.

Because the data fall just within the State’s water quality standards and the watershed is located in a rapidly developing area, Maryland Department of the Environment (MDE) will require that Carroll County develop a Watershed Protection Plan (WPP), otherwise MDE will develop a TMDL to assure the necessary protections.   The WPP is to protect the quality of the water supply source, manage a recreational water resource, and monitor the effects of changes in the watershed that might generate new pollutant sources.  MDE believes such a plan is needed to ensure that there is no additional degradation of water quality that could threaten the reservoir, and will protect water quality sooner and more effectively than a TMDL.  Barring the receipt of any contradictory data, this report will be used to remove Piney Run Reservoir from the 303(d) list on the understanding that a WPP will be completed.  Although the waters of Piney Run Reservoir do not display signs of eutrophication caused by excessive nutrients, the State reserves the right to require additional pollution controls in the watershed if evidence suggests that nutrients from the basin are contributing to downstream water quality problems.  

WQA of Eutrophication for the Piney Run Reservoir
in Carroll County, MD

(Concurrence January 20, 2005)

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.