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Discharge Monitoring Report (DMR) Pollutant Loading Tool

Note: The tool uses discharge monitoring report (DMR) data from ICIS-NPDES and PCS 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, additional errors exist in ICIS-NPDES and PCS. 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 and PCS. 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. The tool also uses wastewater pollutant discharge data from the Toxics Release Inventory (TRI).

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 annual data extracts from EPA’s compliance databases (PCS and ICIS-NPDES). These databases and 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. EPA is unable to identify and correct all the errors in the PCS and ICIS-NPDES databases.

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 PCS and ICIS-NPDES to calculate annual estimates of pollutant discharges.

Using EZ Search (DMR)

The Loading Tool highlights annual estimates of pollutant discharges that are potentially using data outliers. See an example of how the results of an EZ Search (DMR) are highlighted in blue shading.

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

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

From the table in Figure 1 you can click on the highlighted annual discharge estimate (see the “2,896,977” value in the column with the heading of “Total Pounds (lbs/yr)”, which is circled in red for this example). This will direct you to a new page with a new 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 create a new table showing the exact DMR data and formulas used to generate the annual discharge estimate, which 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 example how the Loading Tool calculates annual discharge estimates for a particular facility for a particular pollutant at a particular outfall for a given year. Each row represents a month where monitoring data exists in ICIS-NPDES or PCS. In the example in Figure 3 you can see the average daily value for Nitrogen in March 2010 is 1,074 mg/L (see red circled value), which is significantly different than the other monthly values (e.g., February 2010 is 10.48 mg/L and April 2010 is 10.13 mg/L). The annual discharge amount of Nitrogen for this facility is mostly composed of the March 2010 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 10.74 mg/L and not 1,074 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 Web site for this facility for this year. 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 PCS and ICIS-NPDES to calculate annual estimates of pollutant discharges. See Figure 4.

Figure 4. Facility Loading Calculations Search

Figure 4. Facility Loading Calculations Search

You can use a unique identifier (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 4, you can also click on “Look up facility name” to conduct a search on the facility (as there may be more than one facility with the same name). For example, as shown in Figure 5 there are three facilities with the name “Middletown WWTP.”

Figure 5. Example Results of a Facility Name Search

Figure 5. Example Results of a Facility Name Search (“Middletown WWTP”)

Click on “Search” to return to the Facility Loading Calculations search. As shown in Figure 6, the Loading Tool populates the Facility Loading Calculations search with the name and NPDES ID of the facility you selected.

Figure 6. Facility Loading Calculations Search (Populated after Facility Search)

Figure 6. Facility Loading Calculations Search (Populated after Facility Search)

Click on “Select” to display the pollutants that are discharged at this facility. See Figure 7.

Figure 7. Results of Facility Loading Calculations Search

Figure 7. Results of Facility Loading Calculations Search

As shown in Figure 7 click on “View Details” to drill down to the Facility Loading Calculations table to see how the Loading Tool uses monitoring period data to calculate annual estimates of pollutant discharge amounts. See an example of a Facility Loading Calculations table in Figure 3. 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 Web site for this facility for this year. You can follow the instructions below for how to report this error to EPA Regional and state water data stewards.

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How to Report a DMR Error

After you identify a potential data error you can report this potential error to the appropriate state or EPA data steward through EPA’s ECHO website.

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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 website. First click on “Chemical Discharge to Water” or “POTW Transfer Locations.” See Figure 16.

Figure 16. EPA's Envirofacts Website

Figure 16. 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 17.

Figure 17. EPA's Envirofacts 'Report an Error' Button

Figure 17. 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. Also please include the following:

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

The user can consult these websites on how best to submit a request to update or correct data. Users can also send an e-mail to waterloadings@epa.gov with any comments or questions about the tool.

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About the Data Glossary Error Correction Contact Us

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