Discharge Monitoring Report (DMR) Pollutant Loading Tool
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Note: The tool uses discharge monitoring report (DMR) data from ICIS-NPDES to calculate pollutant discharge amounts. 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. Due to the large amount of DMR data, some errors exist in ICIS-NPDES DMR data. Please see the User Guides page for instructions on how to use the tool and how to correct errors in ICIS-NPDES. The tool also uses wastewater pollutant discharge data from the Toxics Release Inventory (TRI). Contact Us with any comments or questions about the tool, and sign up for our e-mail news bulletin to be notified when new data, enhancements, or training materials become available.
The DMR Pollutant Loading Tool ("Loading Tool") calculates wastewater pollutant discharge amounts (e.g., pounds per year or monitoring period) from NPDES regulated facilities to surface waters (e.g., lakes, rivers, streams) using weekly data extracts from EPA's compliance database (ICIS-NPDES). This database and the underlying data are owned and maintained by EPA's Office of Enforcement and Compliance Assurance (OECA). EPA has verified the accuracy of the DMR Pollutant Loading Tool calculations, and has conducted a preliminary review of the tool output to verify the accuracy of the underlying DMR data used for the calculations. However, EPA's review of the underlying data has focused on the highest discharges and included a limited number of facilities. Due to the large amount of DMR data, some errors exist in ICIS-NPDES DMR data.
The Loading Tool also presents the annual estimates of wastewater pollutant discharge amounts from TRI reporters to surface waters and municipal sewage treatment plants (a.k.a. Publicly Owned Treatment Works (POTWs)) using EPA's TRI database. This database is owned and maintained by EPA's Office of Environmental Information (OEI). The TRI Program conducts a number of activities every year to ensure the quality of TRI data reported to EPA. These activities range from providing extensive reporting guidance, intelligent reporting software, and training to facilities prior to the reporting deadline as well as data validation and analysis after the data are received. Even with all of these efforts to improve data quality EPA is unable to identify and correct all the errors in the TRI database. See the TRI Data Quality Program Information web page for more information on these activities.
This page contains information to help users:
- Investigate potential DMR errors using the Loading Tool,
- Report potential DMR errors using ECHO Effluent Charts,
- Investigate and report potential TRI errors, and
- Investigate other data used by the Loading Tool.
You can use EZ Search (DMR) or the Facility Loading Calculations search on the Everyday Searches tab to investigate how the Loading Tool uses monitoring data in ICIS-NPDES to calculate annual estimates of pollutant discharges.
Using EZ Search (DMR)
The Loading Tool flags annual estimates of pollutant discharges that using DMR data that are potential outliers. See Figure 1 as an example below.
From the table in Figure 1, you can click on the annual discharge estimate (see the "5,249,783" value in the column with the heading of "Total Pounds (lbs/yr)"). This will direct you to a new page with a table showing the annual discharge estimate in question for the facility and the corresponding outfall(s) for this pollutant. See Figure 2.
Click on the “View Details” button, which will display a new table showing the underlying DMR data and formulas used to generate the annual discharge estimate. The estimate will be specific to a particular facility, outfall, pollutant, and year. See Figure 3.
Figure 3 shows an example of how the Loading Tool calculates annual discharge estimates for a particular facility, pollutant, and outfall for a given year. Each row represents a month where monitoring data exists in ICIS-NPDES. In the example in Figure 3, you can see the average daily value for Nitrogen in October 2012 is 5,185 mg/L (see red circled value), which is significantly different than the other monthly values (e.g., July 2012 is 7.407 mg/L and November 2012 is 5.98 mg/L). The annual discharge amount of Nitrogen for this facility is mostly composed of the October 2012 monitoring period load. In this example, there is likely a data entry error with the omission of a decimal point (i.e., value should likely be 5.185 mg/L and not 5,185 mg/L).
Below the Facility Loading Calculations Table is a button labeled “Report DMR Error.” Click on this button to launch the EPA’s ECHO Effluent Charts for this facility. You can follow the instructions below for how to report this error to EPA Regional and state water data stewards.
Using the Facility Loading Calculations Search
You can use the Facility Loading Calculations search on the Everyday Searches tab to investigate how the Loading Tool uses monitoring data in ICIS-NPDES to calculate annual estimates of pollutant discharges. See Figure 4. You can use a unique identifier (Facility Registry Service (FRS) ID or NPDES Permit ID) or the FRS facility name to identify the facility. If you have the facility's unique identifier, you can enter it in this search and click on "Search."
As shown in Figure 5, click on “View Details” to drill down to the Facility Loading Calculations table to the one or more outfalls that are discharging the selected parameter. Then, click on the outfall that is of interest to you (see Figure 6) to view monitoring period level calculations.
Figure 7 shows the Facility Loading Calculations table (monitoring period level), which you can use to identify potential data errors. Click on the button labeled “Report DMR Error” to launch the EPA’s ECHO Effluent Charts for this facility. You can follow the instructions below for how to report this error to EPA Regional and state water data stewards.
After you identify a potential data error, you can report it to the appropriate state or EPA data steward through EPA’s ECHO website. Please refer to ECHO's How to Report an Error and Effluent Charts Help. The ECHO Tutorials page provides a video tutorial describing how to use the Effluent Charts and error reporting functionality.
You can report a potential error in the TRI database by going to EPA’s Envirofacts - TRI EZ Search. First click on “Chemical Discharge to Water” or “POTW Transfer Locations.” See Figure 8.
In the box labeled “TRI Links,” which is on the right hand side of the page, click on the red button labeled “Report an Error.” See Figure 9.
You can then follow the instructions on the form to report a potential error. Please be specific by including as much relevant information about the error as you can provide, such as the following information:
- Facility identification information (preferably the TRI ID);
- Chemical name;
- The reporting year for the data field in question;
- Whether the release was to a surface water or POTW; and
- Any other information that would be useful for the data steward to review your request for a data correction.
In a similar process as described above, data corrections will be routed through the EPA’s Integrated Error Correction Process. Any corrections made to the TRI database will be incorporated in the next monthly refresh of the database supporting the Loading Tool.
The Loading Tool uses other data sources including:
- EPA Watershed Assessment Tracking and Environmental ResultS (WATERS) Web services - information about receiving waterbodies. WATERS derives some its data from the following databases:
- EPA Clean Watershed Needs Survey (CWNS) - information about treatment technologies in place at municipal wastewater treatment plants (a.k.a. Publicly Owned Treatment Plants (POTWs));
- EPA Facility Registry Service (FRS) - facility location information and linking ICIS-NPDES facilities to other EPA programs, such as the Toxics Release Inventory (TRI);
- EPA Substance Registry Services (SRS) - the Agency's central system for information about substances that are tracked or regulated by EPA or other sources. It is the authoritative resource for basic information about chemicals, biological organisms, and other substances of interest to EPA and its state and tribal partners; and
- EPA STORET (short for STOrage and RETrieval) Data Warehouse - a repository for water quality, biological, and physical data.
Users can consult these websites on how best to submit a request to update or correct data. Users may also contact us with any comments or questions about the tool.
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