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Discharge Monitoring Report (DMR) Pollutant Loading Tool

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 Guide (29 pp, 2.6MB), Frequently Asked Questions and Answers, and Error Correction 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). You can send an email to waterloadings@epa.gov with any comments or questions about the tool. You can sign up for our e-mail news bulletin and be notified when new data, enhancements, or training materials are available.

EPA is working to resolve a problem with linkages in EPA's Facility Registry Service (FRS) for Clean Water Act permits. Read More...

Error Corrections

Overview

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:

How to Investigate a Potential DMR Error

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.

Figure 1. Showing Annual Estimates that are Calculated from Potential Data Outliers

Figure 1. Blue Flag Indicating Annual Estimates that are Calculated from Potential DMR Data Outliers

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.

Figure 2. Table Showing Annual Discharge Estimate with Corresponding Outfall(s)

Figure 2. Table Showing Annual Discharge Estimate with Corresponding Outfall(s)

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. Facility Loading Calculations Table

Figure 3. Facility Loading Calculations Table

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.

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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."

Figure 4. Facility Loading Calculations Search

Figure 4. Facility Loading Calculations 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 5. Results of Facility Loading Calculations Search

Figure 5. Results of Facility Loading Calculations Search

 

Figure 6. Facility Loading Calculations Search (Outfall Level)

Figure 6. Facility Loading Calculations (Outfall Level)

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.

Figure 7. Facility Loading Calculations Search (Monitoring Period Level)

Figure 7. Facility Loading Calculations (Monitoring Period Level)

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How to Report a DMR Error

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.

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How to Report a TRI Error

You can report a potential error in the TRI database by going to EPA’s Envirofacts web site - TRI EZ Search. First click on “Chemical Discharge to Water” or “POTW Transfer Locations.” See Figure 8.

Figure 8. EPA's Envirofacts Website

Figure 8. EPA’s Envirofacts Website (Useful for Exploring TRI Data)

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.

Figure 9. EPA's Envirofacts 'Report an Error' Button

Figure 9. EPA's Envirofacts "Report an Error" Button

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:

  1. Facility identification information (preferably the TRI ID);
  2. Chemical name;
  3. The reporting year for the data field in question;
  4. Whether the release was to a surface water or POTW; and
  5. 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.

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How to Investigate Other Data Used by the Loading Tool

The Loading Tool uses other data sources including:

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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About the Data Glossary Error Correction Contact Us

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