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EPA Releases DMR Pollutant Loading Tool

Grayson_Lynn_COLORBy E. Lynn Grayson


EPA recently released the Discharge Monitoring Report (DMR) Pollutant Loading Tool designed to help individuals determine who is discharging, what pollutants they are discharging and how much, and where they are discharging. The tool calculates pollutant loadings from permit and DMR data from EPA's Permit Compliance System (PCS) and Integrated Compliance Information System for the National Pollutant Discharge Elimination System (CIS-NPDES). Data is available for the years 2007 through 2010. Pollutant loadings are presented as pounds per year and as toxic-weighted pounds per year to account for variations in toxicity among pollutants. The tool ranks dischargers, industries, and watersheds based on pollutant mass and toxicity, and presents "top ten" lists to help you determine which discharges are important, which facilities and industries are producing these discharges, and which watersheds are impacted.

The tool also includes wastewater pollutant discharge data from EPA's Toxics Release Inventory (TRI). Data is available for the years 2007 through 2010. Users can search TRI data to find the facilities with the largest pollutant discharges to surface waters or sewage treatment plants (a.k.a. Publicly-Owned Treatment Works – "POTWs"). Users can also compare the DMR data search results against TRI data search results and vice versa. The tool clearly labels the source of data when displaying search results but does not mix TRI or DMR data when calculating pollutant discharges.

The Loading Tool uses discharge monitoring and permit data from PCS and ICIS-NPDES. PCS and ICIS-NPDES are databases that automate entering, updating, and retrieving discharge monitoring and permit data:

  • PCS and ICIS-NPDES are national in scope, including data from all 50 states and 21 U.S. territories and tribes;
  • PCS and ICIS-NPDES contain discharge data that facilities determine through effluent chemical analyses and metered flow; and
  • PCS and ICIS-NPDES collectively include information for facilities in all point source categories that discharge directly to receiving streams.

EPA has verified the accuracy of the tool's calculations. EPA has also performed a limited review of the underlying data that has focused on facilities with the largest amounts of pollutant discharges.

DMR data has long been a key source of citizen suits under the Clean Water Act. With the creation of this new tool, this data will be more easily obtained and available in a more user friendly format.

The tool is available at