Jump to main content or area navigation.

Contact Us

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.

About the Data

Data Sources for the DMR Pollutant Loading Tool

The Loading Tool uses discharge monitoring and permit data from ICIS-NPDES. ICIS-NPDES is a database that automate entering, updating, and retrieving discharge monitoring and permit data.

Dischargers submit discharge monitoring data to their permitting authority using discharge monitoring report (DMR) forms. The permitting authority then enters these data into ICIS-NPDES and checks whether the discharger is in compliance with the NPDES permit requirements. Facilities report pollutant discharge monitoring data in their DMR as mass-based quantities (e.g., pounds per day) and/or concentrations (e.g., mg/L); however, discharges are reported using a wide variety of units.

Permit data include NPDES permit limits for water quality parameters (e.g., dissolved oxygen and temperature), specific chemicals (e.g., phenol), bulk parameters (e.g., biochemical oxygen demand), and flow. The permitting authority enters these data into ICIS-NPDES. ICIS-NPDES also include information on the facility’s permit requirements, such as monitoring frequency. The ICIS-NPDES database:

  • Is national in scope, including data from all 50 states and 21 U.S. territories and tribes;
  • Contains discharge data that facilities determine through effluent chemical analyses and metered flow; and
  • Include information for facilities in all point source categories that discharge directly to receiving streams.

The tool also includes wastewater pollutant discharge data from EPA’s Toxics Release Inventory (TRI). Data is available for the years 2007 through 2012. 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 or “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. See the Basics of TRI Reporting and Factors to Consider When Using TRI Data (PDF) (37 pp, 1MB) for more information.

Other data sources used by the Loading Tool include:

  • Watershed Assessment Tracking and Environmental ResultS (WATERS) Web services for retrieving information about receiving waterbodies. WATERS derives some its data from EPA’s Assessment, TMDL Tracking and ImplementatioN System (ATTAINS) database, USGS Geographic Names Information System (GNIS), and the USGS National Hydrography Dataset (NHD);

  • 2008 Clean Watershed Needs Survey (CWNS) for providing information about treatment technologies in place at municipal wastewater treatment plants (a.k.a. Publicly-Owned Treatment Plants or POTWs);

  • EPA’s Facility Registry System (FRS) for providing facility location information and linking ICIS-NPDES facilities to other EPA programs, such as the Toxics Release Inventory (TRI);

  • EPA’s Substance Registry Services (SRS), which is 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's STORET (STOrage and RETrieval) Data Warehouse, which is a repository for water quality, biological, and physical data.

DMR Loading Tool Database Sources and Updates
Data Source Contact Process Schedule
ICIS-NPDES EPA/OEI Prior to 2014, obtained annual dmp of 20 ICIS tables and restore to ICISONE schema. After 2014, extract data from greyhound via database link using CDC process. Continuous
TRI EPA/OEI Download US 1 and 3b tables from TRI website. Annual
TRI Pollution Wastewater Treatment Information EPA/OEI Via webservice Annual
CWNS EPA/OWM Send email request for CWNS database tables. In the past, provided as excel files. Every 4 years
FRS EPA/OEI Can be included in the ICIS-NPDES extraction. Previously requested dmp file of NPDES_SITE table, but can retrieve directly from ICIS. Annual
SRS EPA/OEI Send email request for latest SRS tables. In the past, provided as excel files. Annual
Crosswalk linking pollutants contributing to a waterbody impairment ERG    
Impaired Waterbodies EPA STORET Via webservice  
Counties with ESA-listed aquatic species U. S. Fish and Wildlife Service, ECOS PM Send email to U.S. Fish and Wildlife Service asking for new data file from their ECOS database. Annual
HUC12s INDUS Currently run batches on web services to populate database tables with HUC 12 information. Annual
Steam Electric Industry - EIA/NPDES ID Match-Up EPA/OW Send email request for latest table. In the past, provided as excel files. Update via error correction
Facility Program Flags
CWA Pretreatment Program Flag (PRET) EPA/OWM Send email to request updated facility list (in excel) Update via error correction
POTWs with Combines Sewer Overflows (CSOs) EPA/OWM Send email to request updated facility list (in excel) Update via error correction
Pesticide-Producing Establishments Envirofacts See http://www.epa.gov/envirofw/html/fii/prog_sys.html Annual
Abandoned Haz Waste Sites Envirofacts See http://www.epa.gov/envirofw/html/fii/prog_sys.html Annual
Oil Spill Prevention Program Envirofacts See http://www.epa.gov/envirofw/html/fii/prog_sys.html Annual
Facilities in Chesapeake Bay TMDL Chesapeake Bay TMDL, Appendix Q Send email to request updated facility list (in excel). Update via error correction

Top of Page

Data Scope and Limitations

Before you begin your searches, there are some things you should know about the scope and limitations of the pollutant loadings calculated by the Loading Tool:

DMR Data

Facility Universe

While the Loading Tool includes discharges for more than 44,000 facilities, it is not a complete inventory of all discharges permitted under the Clean Water Act.

Although the Clean Water Act requires all point source dischargers to obtain a NPDES permit and monitor their wastewater, not all facility, permit, or discharge monitoring data are uploaded into ICIS-NPDES. EPA places greater priority on major facilities, and requires authorized states to provide more information about the compliance status of these dischargers. Specifically, EPA policy requires the permitting authority to enter facility, permit, and DMR information from “major” dischargers into either ICIS-NPDES. EPA policy requires a more limited set of data be shared with EPA through data entry into ICIS-NPDES (PDF) (14 pp, 4.6 M) for “non-major” (or “minor”) facilities. Many authorized states also transmit facility, permit, and DMR data for non-major dischargers to the ICIS-NPDES databases. The links below detail the amount of DMR data that the states share with EPA’s ICIS-NPDES database. These data come from EPA’s State Review Framework, which allows EPA to identify recommendations for improvement to ensure fair and consistent enforcement and compliance programs across the states. There are also differences between the states on sharing facility level data with EPA’s ICIS-NPDES database for general permit covered facilities (e.g., oil and gas extraction facilities, construction stormwater sites). EPA and states issue general permits to increase the efficiency of the permit program as multiple similar facilities can be regulated under one permit.

Download state statistics and loadings for:

The Loading Tool contains information for industrial and municipal point source dischargers. Other types of Clean Water Act releases that are not available in the Loading Tool include:

  • Wastewater releases from industrial facilities that are connected to a publicly-owned treatment works (POTW) sewerage system, regulated through the CWA Pretreatment Program;
  • Biosolids monitoring data, regulated through the CWA Biosolids Program;
  • Discharges related to wet-weather events, such as stormwater from municipal separate storm sewer systems (MS4s), stormwater from industrial facilities, discharges from construction activities, combined sewer overflows, sanitary sewer overflows, and concentrated animal feeding operations (CAFOs).

Pollutant Universe

The Loading Tool includes approximately 1,000 pollutant parameters including specific chemicals (e.g., phenol), bulk parameters (e.g., biochemical oxygen demand), temperature, and wastewater flow. However, these pollutants do not account for all pollutants discharged to U.S. waters.

  • ICIS-NPDES only includes information about discharges of pollutants that a facility is required by permit to monitor; facilities are not required to monitor or report all pollutants they actually discharge.
  • Discharge data are entered into ICIS-NPDES using a variety of measurement units. The Loading Tool can only calculate mass discharges for pollutants that are measured either as mass quantities or concentrations. Therefore some pollutants, such as toxicity parameters measured as percent, are excluded from the Loading Tool. Further, the Loading Tool cannot calculate a load for concentration measurements if a wastewater flow measurement is not provided.

Additionally, EPA policy requirement requires a more limited set of facility, permit and DMR data be shared with EPA through data entry into ICIS-NPDES for non-major facilities. Data sharing for these non-major facilities varies across the different state NPDES permit programs. Consequently, the Loading Tool will not identify all non-major facilities if you limit a search to a particular pollutant. The Loading Tool uses permit data to count facilities when the user searches on a particular pollutant.

Matching Facilities to Watersheds

The Loading Tool matches facilities to receiving watersheds based on a facility’s latitude and longitude coordinates and watershed spatial data in the Natural Resources Conservation Service’s Watershed Boundary Dataset. The Loading Tool cannot establish a match between a facility and a watershed if either:

  • The facility does not have latitude or longitude coordinates; or
  • There are no spatial data for the receiving watershed.

The Loading Tool uses names from the USGS Geographic Names Information System (GNIS). The GNIS is closely integrated with the National Hydrography Dataset (NHD), which makes these data more useful for plotting on maps and for watershed modeling and other research. Not all waterbodies receiving wastewater discharges have names in the GNIS and the not all names in the GNIS match the names that facilities provide in their NPDES permit application.

See Watershed Data for further information about how the Loading Tool matches DMR facilities to receiving watersheds.

Data Quality

DMR data may be entered into the ICIS-NPDES database manually, which can lead to data-entry errors. The database supporting this online tool uses data extracts from ICIS with regular error correction updates from EPA's Integrated Error Correction Process. The Integrated Error Correction Process allows EPA to track and incorporate into the Loading Tool database error corrections submitted by the public. EPA also works with states to identify any error corrections that they make to their data outside of the Integrated Error Correction Process.

Intermittent Dischargers

Some facilities have intermittent discharges and may have one or more outfalls that don’t discharge for one or more months. ICIS-NPDES has ways of identifying when there is no discharge at a particular outfall for an entire monitoring period. In such cases, the Loading Tool does not calculate pollutant loads for these outfalls during these monitoring periods.

EPA also developed a methodology with the states to estimate intermittent discharges that occurring within a monitoring period (e.g., there is a discharge from the outfall but it only occurs two days out of the monthly monitoring period). Specifically, the Loading Tool uses three ICIS-NPDES "Duration of Discharge" codes for identifying these intermittent dischargers: 50037, 82517, and 81381. The Loading Tool will automatically adjust the pollutant loading calculation such that the calculation only estimates pollutant discharges for the time when the outfall is discharging (e.g., two days in the month instead of the entire month).

However, there is a limitation with ICIS-NPDES data in that not all NPDES permits require permittees to submit these Duration of Discharge codes when there are intermittent discharges that occur within a monitoring period. Consequently, the tool may overestimate pollutant discharges for these intermittent dischargers that do not report these Duration of Discharge codes. NPDES permittees with intermittent discharges are encouraged to engage with their permit writers to add one of these Duration of Discharge codes to their DMR. NPDES permittees may also contact EPA (waterloadings@epa.gov) if these Duration of Discharge codes are not yet in their DMR.

TRI Data

Facility Universe

TRI reporting is limited to industrial facilities (i.e., POTWs do not report to TRI) and not all industry sectors report to TRI. Additionally, small establishments (less than 10 employees) are not required to report, nor are facilities that don't meet the reporting thresholds. Thus, facilities reporting to TRI may be a subset of an industry. See the Basics of TRI Reporting and Factors to Consider When Using TRI Data (PDF) (37 pp, 1 M) for more information.

Pollutant Universe

TRI reporting focuses on toxic pollutant discharges and does not include common wastewater pollutants like Total Suspended Solids and Biochemical Oxygen Demand, which can be important factors when assessing the potential impact to surface waters. Additionally, the TRI Program doesn’t require additional monitoring, so reported releases are often, in part, based on estimates, not measurements, and, due to TRI guidance, may differ greatly from DMR data, especially at facilities with large wastewater flows. Finally, certain chemicals (polycyclic aromatic compounds [PACs], dioxin and dioxin-like compounds, metal compounds) are reported as a class, not as individual compounds. Because the individual compounds in most classes have widely varying toxic effects, the potential toxicity of chemical releases can be inaccurately estimated.

Matching Facilities to Watersheds or to POTWs

TRI reporting does require facilities to report the names of the surface waterbodies and POTWs that receive their wastewater discharges. See Sections 5.3 and 6.1 in TRI Form R. However, these reported names are not standardized or indexed to USGS's NHD or EPA’s Federal Registry System (FRS).

See Watershed Data for further information about how the Loading Tool matches TRI facilities to receiving watersheds.

Data Quality

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. See the TRI Data Quality Program Information page for more information on these activities.

Top of Page

Watershed Data and Maps

In addition to calculating pollutant loads, the Loading Tool matches pollutant discharges to receiving watersheds and retrieves the name of the receiving waterbody and available information about its impairment status.

The U.S. Geologic Service (USGS) defines watersheds in the U.S. and Caribbean using unique Hydrologic Unit Codes (HUC). These codes consist of two to twelve digits based on six levels of classification:

  • Region (first-level, 2-digit HUC);
  • Subregion (second-level, 4-digit HUC);
  • Accounting unit (third-level, 6-digit HUC);
  • Cataloguing unit (fourth-level, 8-digit HUC);
  • Watershed (fifth-level, 10-digit HUC); and
  • Subwatershed (sixth-level, 12-digit HUC).
The Loading Tool uses the 12-digit HUC (HUC-12) to identify watersheds in its searches. The Loading Tool uses HUC-12s to define major U.S. watersheds to provide geographic search criteria for EZ Search, TRI Search, Advanced Search and several Everyday Searches. Please review HUC Maps and Codes for Major U.S. Watersheds for more details.

The Loading Tool relates facility discharges to HUC-12s and uses the HUC-12s to retrieve other watershed information. Figures 1 and 2 present flow charts describing how the Loading Tool uses Watershed Assessment Tracking and Environmental ResultS (WATERS) web services to identify receiving watersheds and pull receiving water information. Table 1 describes the specific inputs, outputs, and URLs used to obtain watershed information for the Loading Tool.

Figure 1. Primary Loading Tool Use of WATERS Web Services for Facility Search

Figure 2. Secondary Loading Tool Use of WATERS Web Services for Facility Search

Matching Facility Discharges to HUC-12s

The Loading Tool uses a mapping service developed by Office of Water to link facilities to HUC-12s: OWRAD/PCS_WMERC. This mapping service contains GIS data for facilities in the Watershed Assessment Tracking and Environmental ResultS (WATERS) database and overlays the facility data with HUC-12 polygons from the Natural Resources Conservation Service’s Watershed Boundary Dataset. The service returns the HUC-12 that has the greatest overlap with the facility’s spatial data.

The WATERS database uses SOURCE_FEATURE_IDs to uniquely identify point source discharges. The SOURCE_FEATURE_ID is unique for each facility outfall in the WATERS database (a single facility may have multiple outfalls). The ID contains nine to twelve characters. The first nine characters are the facility’s NPDES permit number (e.g., DC0000094).

  • If the facility has only one outfall, then the NPDES permit number is the SOURCE_FEATURE_ID.
  • If the facility has multiple outfalls, then the SOURCE_FEATURE_ID is the NPDES permit number plus the three character code for the outfall (e.g., DC0000094001).
EPA's Office of Water provided a list of SOURCE_FEATURE_IDs from the WATERS database, and EPA matched this list to facilities in the Loading Tool database.

To simplify its searches, the Loading Tool only identifies one HUC-12 for each facility. Therefore, the Loading Tool database only matches one SOURCE_FEATURE_ID to each facility. If a facility has multiple SOURCE_FEATURE_IDs, then the Loading Tool only selects the first SOURCE_FEATURE_ID that matches to that facility. As shown in Figure 2, the Loading Tool passes the SOURCE_FEATURE_ID to the OWRAD/PCS_WMERC mapping service and the mapping service returns the matching HUC-12 from the Watershed Boundary Dataset.

Retrieving Water Information

The detailed Facility Results page in the Loading Tool presents information about the receiving water, including the HUC-12, the Waterbody Name, REACH Code, and an indicator for whether the stream is listed on EPA’s 303d list of impaired waters. The previous section described how the Loading Tool obtains a HUC-12 for each facility. The Loading Tool uses the WATERS web services, described below, to obtain additional waterbody information. Figures 1 and 2, above, show the data flow between the Loading Tool and the WATERS web services that the tool uses to obtain receiving water information. Table 1 provides further information about web services consumed by the Loading Tool.

  • NPDES: The Loading Tool uses this service to obtain the REACH Code, GNIS (geographic waterbody name) and identify whether a receiving stream is listed on EPA’s 303d list of impaired waters. The service also provides the impairment classification and impairment cause for impaired waters. The Loading Tool passes a NPDES ID to the web service and the NPDES service returns the watershed information. The data flow is shown in Figure 1. If the NPDES service does not return any watershed information, the Loading Tool uses a secondary method to obtain watershed information, as shown in Figure 2.

  • OW/WBD_NAD83: The Loading Tool uses this service to pull the HUC-12 name from the Watershed Boundary Dataset.

  • OWRAD/PCS_WMERC: The Loading Tool uses this service to obtain the REACH code for the receiving stream. The Loading Tool also uses this service to identify the HUC-12 for the receiving watershed, as described in the previous section. To obtain the REACH code, the Loading Tool passes a SOURCE_FEATURE_ID to the OWRAD/PCS_WMERC look-up service, and the look-up service pulls the REACH code from the WATERS Reach Address Database (RAD).

  • REACH_to_GNIS: The Loading Tool uses this service to pull the waterbody name for the receiving stream. The Loading Tool passes the REACH code obtained from the OWRAD/PCS_WMERC web service to the REACH_to_GNIS look-up service. The look-up service returns the waterbody name from USGS’s Geographic Names Information System (GNIS).

  • OWRAD/303D_WMERC: The Loading Tool uses this service to identify whether a receiving stream is listed on EPA’s 303d list of impaired waters. The service provides access to impaired waters data stored in EPA’s Assessment and TMDL Tracking and Information System (ATTAINS). The Loading Tool passes each facility’s SOURCE_FEATURE_ID to the web service. If there is a matching SOURCE_FEATURE_ID in OWRAD/303D_WMERC, then the loadings tool flags the facility as discharging to an impaired waterbody. Note the Clean Water Act Section 303(d) list of impaired waters does not include all impaired waters reported in a state’s Integrated Report. It does not include the following:
    • Waters that are impaired but have an EPA-approved TMDL established;
    • Impaired waters for which other pollution control mechanisms are in place and expected to attain water quality standards; or
    • Waters where the impairment is the result of pollution that is not the result of a specific pollutant (substance) for which a TMDL can be reasonably developed.

  • UPSTREAM/DOWNSTREAM: The Loading Tool uses this service to obtain the locations and unique identifiers of the nearest upstream and downstream watershed monitoring stations from the facility. The map on the Facility Results page displays the station locations and provides a link to additional station information from EPA’s STOrage and RETrieval Data Warehouse (STORET).

Table 1. Waters Services Consumed by the DMR Pollutant Loadings Tool

Area of DMR LT


Value(s) Passed

Value(s) Received



Facility Search

Waterbody Name

Watershed Name
- Watershed impairment classification flag: (1, 2, 3, 4a, 4b, 4c, or 5)
- Specific cause(s) of impairment


REACH code
GNIS (geographic name)
Impairment status
Impairment classification flag
Impairment cause

http://ofmpub.epa.gov/waters10/npdes_services.get_npdes_info?p_npdes_id= [NPDES ID]


Facility Search

Obtain HUC12 for NPDES ID



http://watersgeo.epa.gov/ArcGIS/rest/services/OWRAD/PCS_WMERC/MapServer/0/query?where=SOURCE_FEATUREID='[NPDES ID var]'&returnGeometry=false&outFields=WBD_HUC12&f=json

Facility Search

Obtain HUC12 for Feature ID (used if above does not return a value)

Feature ID


http://watersgeo.epa.gov/ArcGIS/rest/services/OWRAD/PCS_WMERC/MapServer/0/query?where=SOURCE_FEATUREID='[Feature ID var]'&returnGeometry=false&outFields=WBD_HUC12&f=json

Facility Search

Obtain REACH code for a facility

NPDES ID (as Source Feature ID)


http://watersgeo.epa.gov/ArcGIS/rest/services/OWRAD/PCS_WMERC/MapServer/0/query?where=SOURCE_FEATUREID='[Facility NPDES ID]'&returnGeometry=false&outFields=REACHCODE&f=json

Facility Search

Obtain REACH code for a facility (used if above does not return a value)

NPDES ID (as Source Feature ID)


http://watersgeo.epa.gov/ArcGIS/rest/services/OWRAD/303D_WMERC/MapServer/0/query?where=SOURCE_FEATUREID='[Facility NPDES ID]'&returnGeometry=false&outFields=REACHCODE&f=json

Facility Search

Is HUC12 listed for impairment?


Any data returned = Listed for Impairment

http://watersgeo.epa.gov/ArcGIS/rest/services/OWRAD/303D_WMERC/MapServer/find?searchText=[HUC12 var] &contains=true&searchFields=WBD_HUC12&sr=&layers=0,1,2&returnGeometry=false&f=json

Facility Search

Obtain waterbody name

REACH code

GNIS (geographic name)

http://iaspub.epa.gov/waters10/WATERS_LOOKUP.ReachcodeToGNIS?pReachcode=[REACH code var]

Facility Search

Plot on Google map markers showing the nearest upstream and downstream STORET watershed monitoring stations with links in the pop-up bubbles to their station information page.

REACH code

For each station:
org_id and station_id (to plug in hyperlink to station page)

WATERS Upstream/Downstream JavaScript Library Service:
http://ofmpub.epa.gov/waters10/UpstreamDownStream.Service?pNavigationType=[upstream = UT or UM; downstream = DD or DM] &pStartReachcode= [REACH code]&pTraversalSummary=TRUE&pFlowlinelist=FALSE&pEventList=STORET&pStopDistancekm=50


Obtain HUC12 for Feature ID

Feature ID


http://watersgeo.epa.gov/ArcGIS/rest/services/OWRAD/PCS_WMERC/MapServer/0/query?where=SOURCE_FEATUREID='[Feature ID var]'&returnGeometry=false&outFields=WBD_HUC12&f=json


Obtain HUC name for HUC12



http://watersgeo.epa.gov/ArcGIS/rest/services/OW/WBD_NAD83/MapServer/5/query?text=&returnGeometry=false&where=HUC_12=[ HUC12 var]&outFields=HU_12_NAME,HU_10_NAME,HU_8_NAME&f=json


Obtain impairment cause for NPDES ID


Impairment cause

http://ofmpub.epa.gov/waters10/npdes_services.get_npdes_info?p_npdes_id=[NPDES ID]

EZ Search

Obtain HUC12s in ZIP code

ZIP code

HUC12s within ZIP code


HUC Maps and Codes for Major U.S. Watersheds

The EZ search provides a drop down menu of major US Watersheds that users can select for their query. Many of these watersheds comprise several HUC-12 codes. The maps below show the boundaries of each Major U.S. Watershed as defined by the Loading Tool. EPA’s menu of major U.S. watersheds includes the following:

Top of Page

About the Data Glossary Error Correction Contact Us

Jump to main content.