Total Maximum Daily Load (TMDL) 2018

The Clean Water Act Section 303(d) establishes the Total Maximum Daily Load (TMDL) program. The purpose of the TMDL program is to identify sources of pollution and allocate pollutant loads in places where water quality goals are not being achieved. This layer shows the list of waters for which technology-based or other required pollution controls are not stringent enough to meet water quality standards. The TMDLs themselves specify a pollutant budget that must be achieved to meet state water quality standards and allocates pollutant loads among pollution sources in a watershed, e.g., point and nonpoint sources.
TMDLs can be developed for several categories such as: point sources (permitted sewage and industrial discharges); nonpoint sources (agriculture and urban runoff); lakes; abandoned mine drainage (also called acid mine drainage or AMD); specific bioaccumulative chemicals (PCBs and chlordane that contaminate fish, resulting in fish advisories limiting or banning the number of fish that a person can safely consume); and complex situations (combinations of different types).
This layer is based on the High Resolution National Hydrography Dataset (NHD). The Lake TMDLs are not included in this layer.

This data is hosted at, and may be downloaded or accessed from PASDA, the Pennsylvania Spatial Data Access Geospatial Data Clearinghouse http://www.pasda.psu.edu/uci/DataSummary.aspx?dataset=1130