Water Pollutant Loading Tool - Resources
On this page:
General Resources and Fact Sheets
- About Loading Tool Data
- Hierarchy of Loading Calculations
- Water Pollutant Loading Tool Frequently Asked Questions
- Glossary of Frequent Terms in the Loading Tool
- Linking DMR and TRI Data in the Water Pollutant Loading Tool
- Overview of Loading Tool Architecture
- Technical Users Background Document
- Loading Tool Data Corrections
- Nutrient Aggregation
Technical Reference Documents
Geographic Information
- List of HUC-12s for each Major U.S. Watershed (CSV) (6.1MB)
- Counties with Endangered Species Act (ESA)-listed Aquatic Species (CSV) (70KB)
- Watersheds with Endangered and Threatened Species (XLS) (693KB)
- For more information about ESA-listed species, refer to the U.S. Fish and Wildlife Service Endangered Species Search
Pollutant Information
NPDES DMR Parameters
Select a link to download the parameter and pollutant category lists. The files are refreshed weekly.
- NPDES DMR Parameter to Pollutant Category Crosswalk (CSV) (640 K) - List of DMR parameters from ICIS-NPDES and associated pollutant categories are designated by "Y" flag. This crosswalk is used by the ECHO Wastewater Facility Search and DMR Exceedances Search.
- DMR Pollutant Parameters Used and Not Used by the Loading Tool (CSV) (650 K) – List of DMR pollutant parameters from ICIS-NPDES and pollutant categories are designated by a "Y" flag. This crosswalk is used in the Water Pollutant Loading Tool.
| Element | Description |
|---|---|
| EXCLUDED_FROM_LOADINGS | Indicates those parameters for which loadings cannot be calculated. |
| COUNT_PERMITS_WITH_LIMITS | Indicates the number of distinct NPDES permits that have or had limits and/or monitoring requirements for a parameter at any time between January 1, 2007 to the present. |
| TOXIC_WEIGHTING_FACTOR | The value of the toxic weighting factor, used to convert pounds of pollutant to Toxic Weighted Pounds Equivalent (TWPE). |
| QNCR_POLL_CODE | The Quarterly Noncompliance Report (QNCR) pollutant code indicates whether the parameter is categorized as SNC Group 1, Group 2, or Not Used for the QNCR, for the purposes of calculating reportable noncompliance (RNC). For background on SNC pollutant groupings, refer to the Memorandum: Revision of NPDES Significant Noncompliance (SNC) Criteria to Address Violations of Non-Monthly Average Limits. |
TRI Chemicals
- List of TRI Chemicals (XLS) (374 KB)
- See EPA's TRI program website for information about TRI-Listed Chemicals
- TRI Chemical Removals from Publicly Owned Treatment Works (POTWs) (XLS) (31 KB)
Information pertaining to both DMR and TRI
- Pollutants Contributing to Water Body Impairment: DMR and TRI Parameter to Impairment Category Crosswalk (XLSX) (55KB)
- Comparing CWA NPDES DMR Data and TRI Data (PDF) (20 pp, 735 KB) – Discussion of considerations in comparing DMR and TRI water release data
- DMR /TRI Chemical Group Crosswalk (XLSX) (134 KB)
- Indirect Industrial Discharger Report: Linkage between TRI Facilities and Receiving POTWs (CSV) (28 MB)
- Toxic Weighting Factors (TWFs): DMR Parameter TWFs (CSV) (345 KB) and TRI Chemical TWFs (CSV) (66 KB)
- TWF Development Methodology
- TWF Development Methodology (EPA 820-R-12-005) – Provides discussion of TWF equation, limitations, and appropriate use of the weighting factors
- TRI Dioxin TWF Calculation Methodology: See Section 2.4.3 of EPA's Technical Support Document for the Annual Review of Existing Effluent Guidelines and Identification of Potential New Point Source Categories
- Review and Revision of TWFs for Seven Pollutants: Review of Toxic Weighting Factors in Support of the Final Steam Electric Effluent Limitations Guidelines and Standards (2015)
- TWF Development Database (2007) (ZIP) (2 MB)
- TWF Development Methodology
Facility Program Flags
Note: See About Loading Tool Data for the last update dates for the lists below.
- Municipal Separate Storm Sewer System (MS4) NPDES Permits (XLSX) (80 KB)
- CWA Pretreatment Program Facility List (CSV) (231 KB)
- National Combined Sewer Overflow Inventory
- Pesticide-Producing Establishments List (CSV) (130 KB)
- Abandoned Hazardous Waste Sites List (CSV) (215 KB)
- Oil Spill Prevention Program Facility List (CSV) (455 KB)
- Chesapeake Bay Total Maximum Daily Load (TMDL) Facility List (CSV) (524 KB)
- Steam Electric Industry - EIA/NPDES ID Match-Up (XLSX) (954 KB)
Industrial Classification
Note: As creation of the ZIP files is automated and updated weekly as part of the Loading Tool data refresh, the file sizes below are approximate.
- Standard Crosswalks
- Effluent Guidelines (ELGs) Crosswalks (used only for Top Industrial Dischargers of Toxic Pollutants)