Multi-Year Loading Report Help

The DMR and TRI Multiyear Loading Report provides a side-by-side comparison of DMR and TRI pollutant loads in the last five years. Loads are displayed in pounds or toxic-weighted pounds (TWPE). Each pollutant row also contains a drilldown feature, which displays further detail about the pollutants included in each chemical group. Downloads are available for both the overall chemical group loadings, and individual discharges in the drilldown tables.

Note: When comparing DMR and TRI data, there are some considerations to keep in mind. A facility with data in ICIS-NPDES may not have data in TRI, and vice versa, due to a difference in facility reporting requirements, pollutant reporting requirements, or water discharge types captured. Facilities in ICIS-NPDES and TRI are linked using their Facility Registry Service (FRS) ID. See Linking DMR and TRI Data for more information on data analysis considerations.

Data Dictionary

Facility Registry Service (FRS) ID
A 12-character code used to uniquely identify a facility site within the EPA’s FRS.
National Pollutant Discharge Elimination System (NPDES) ID
A 9-character code used to uniquely identify a permitted NPDES facility. The NPDES permit program regulates the direct discharge of pollutants into U.S. surface waters.
Toxic Release Inventory (TRI) ID
A 15-character code used to uniquely identify facilities in EPA's TRI. This ID is also known as the Toxics Release Inventory Facility Identification Number (TRIFID).
Chemical Group
Chemical grouping developed by EPA to group and link similar DMR parameters with TRI chemicals for comparative analyses. To match DMR data to TRI-reported discharges, and to avoid double-counting within DMR and TRI, EPA groups and sums the pollutant discharges in DMR and TRI data to the chemical group level and matches on a unique chemical group ID. The name of the parameters included in the chemical group can be viewed in the drilldown.
Data Type
Indicates the data source for load calculations. DMR Pollutant data are from ICIS-NDPES, and TRI Chemical data are from TRI.
For DMR loadings, the parameter name in ICIS-NPDES used to identify the substance discharged. For TRI releases, the TRI chemical name.
For basic information about the substances, search for the pollutant/chemical in EPA's Substance Registry Services (SRS).
Pounds (lb/yr)
DMR - Annual mass discharge of a pollutant to a receiving stream calculated using the methodology described in Section 3.3 of the Technical Users Background Document for the DMR Pollutant Loading Tool. See Loading Tool FAQs for more information on DMR loading calculations.
The blue outlier flag indicates a value contains loads that are calculated using data that has been flagged as potential outliers or data errors.
TRI - The annual mass (in units of pounds/year) for direct discharges reported to TRI. Direct discharges are defined as wastewater released directly into U.S. surface waters.
Note: “N/A” indicates the chemical is not covered by the TRI Program, “--" indicates that the pollutant or chemical was not reported in DMR or TRI for the reporting year, and “0” indicates that zero discharge was reported.
TWPE (lb-eq/yr)
TWPE is the mass of a pollutant or chemical discharged that accounts for its relative toxicity, in units of pound-equivalents per year. To convert pollutant loadings into TWPE, EPA multiplies the pollutant mass (in pounds) by its pollutant specific toxic weighting factor (TWF). EPA developed TWFs for use in its effluent limitations guidelines and standards (ELGs) development program to allow comparison of pollutants with varying toxicities. Not all pollutants have a toxic weighting factor (for example, Total Suspended Solids), which means that these pollutants do not have a toxicity score (i.e., TWPE = 0). See Technical Support Documents for more information about TWFs.
Contains Potential Outlier?
A data quality flag to identify potential outliers or data errors in DMR data. “Y” indicates that a pollutant load is calculated from DMR measurements that vary by more than three orders of magnitude during the reporting year.

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