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Total Maximum Daily Loads

Total Maximum Daily Loads (TMDLs) are established when water bodies (streams, rivers, lakes) do not meet water quality standards.  These standards are established by the Maryland Department of the Environment (MDE). 


Each of the County's 8 major watersheds have some sort of impairment.  Using available monitoring data and accepted modeling techniques, the MDE has established specific loads (wasteload allocations) for the County to meet in order to address many of these impairments.  

Graphical map of the County Watersheds on Maryland's Impaired List as of January 2013


Total Maximum Daily Load (TMDL) Watersheds

EPA-approved quantitative assessment studies have established pollutant loading limits (TMDLs) for waterbodies in several County watersheds. These loading limits represent a maximum amount of a pollutant that a waterbody can receive in order to meet water quality standards. The pollutant loading is distributed among various sources of that pollutant (e.g., point sources or nonpoint sources).

Pollutant loading from point and nonpoint sources is reduced by implementing a variety of measures known as best management practices or BMPs. Meeting TMDL loading reductions is a requirement of the County's NPDES MS4 Stormwater Permit.

View Maryland Department of the Environment's TMDL site.