EPA Environmental Dataset Gateway


Open/Close section Identification Information
Title: EPA Office of Water (OW): Nutrient, Sediment, and Pathogens Water Impairments
Abstract: National dataset consisting of a snapshot of 303(d) Listed Impaired Waters combined with Impaired Waters with TMDLs whose parent cause is Nutrients, Sediments, and Pathogens. The snapshot constitutes the top water impairments. The Impaired Waters with TMDLs and the 303(d) Listed Impaired Waters are combined into three mapping service layers in MyWaters Mapper application to provide a comprehensive view of each of these impairments. These waters are linked to the 303(d) information stored in EPAs Assessment and TMDL Tracking and Implementation System (ATTAINS). Below is a brief description of the two programs. The 303(d) Listed Impaired Waters program system provides impaired water data and impaired water features reflecting river segments, lakes, and estuaries designated under Section 303(d) of the Clean Water Act. Each State will establish Total Maximum Daily Loads (TMDLs) for these waters. Note the CWA Section 303(d) list of impaired waters does not represent 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 impaired as a result of pollution and is not caused by a pollutant; therefore, the "Impaired Waters" layers do not represent all impaired waters reported in a state's Integrated Report, but only the waters comprised of a state's approved 303(d) list. For more information regarding impaired waters refer to EPA's Integrated Reporting Guidance at: http://www.epa.gov/owow/tmdl/guidance.html 303(d) Waterbodies are coded onto NHD linear and area features to create Linear, Polygonal and Point Events. Point events represent impaired waterbody segments that do not fall on an NHD reach. 303(d) Waterbodies are coded onto NHD Waterbody reaches (region.rch) to create datasets. In addition to NHD reach indexed data there may also be custom event data (point, line, or polygon) that are not associated with NHD and are in an EPA standard format that is compatible with EPA's Reach Address Database. These custom features are used to represent locations of 303(d) waterbodies that are not represented well in NHD. The Total Maximum Daily Load (TMDL) Tracking System contains information on waters that are Not Supporting their designated uses. These waters are listed by the state as impaired under Section 303(d) of the Clean Water Act. The status of TMDLs are also tracked. TMDLs are pollution control measures that reduce the discharge of pollutants into impaired waters. A TMDL or Total Maximum Daily Load is a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards, and an allocation of that amount to the pollutant's sources. What is a total maximum daily load (TMDL)? Water quality standards are set by States, Territories, and Tribes. They identify the uses for each waterbody, for example, drinking water supply, contact recreation (swimming), and aquatic life support (fishing), and the scientific criteria to support that use. A TMDL is the sum of the allowable loads of a single pollutant from all contributing point and nonpoint sources. The calculation must include a margin of safety to ensure that the waterbody can be used for the purposes the state has designated. The calculation must also account for seasonal variation in water quality. The Clean Water Act, section 303, establishes the water quality standards and TMDL programs.
Purpose: To provide three national snapshots of the top water impairments: Nutrients, Sediment, and Pathogens for the MyWaters Mapper application (http://map24.epa.gov/mwm).
Open/Close section Distribution Information
Resource(Server) URL: https://watersgeo.epa.gov/arcgis/rest/services/OWOTHER/TOPWATERIMP/MapServer
Download URL: https://www.epa.gov/waterdata/waters-geospatial-data-downloads
Open/Close section Time Period of Content
Publication Date: 20100108
Progress: In work
Frequency: Continual
Open/Close section Single Date
Date: 20100108
Currentness: Publication date
Open/Close section Spatial Domain
West Bounding Longitude: -160
East Bounding Longitude: -64
North Bounding Latitude: 50
South Bounding Latitude: 17
Zoom to the metadata envelope
Open/Close section Constraints
License https://edg.epa.gov/EPA_Data_License.html
Access: None
Use: None. Please check sources, scale, accuracy, currentness and other available information. Please confirm that you are using the most recent copy of both data and metadata. Acknowledgement of the EPA would be appreciated.
Open/Close section Theme Keywords
Theme Topics: impaired waters, 303d, TMDL, clean water act, map service, waters10, listed waters, total maximum daily loads, TMDLs, feature service, CWA, point source, GIS, EPA, Stream, reach
Open/Close section Contact Information
Originator: US Environmental Protection Agency, Office of Water
Email: waters_support@epa.gov
Address Type: mailing address
City: Washington
State: DC
Postal Code: 20460
Telephone: 202-566-1145
Open/Close section Metadata Reference Information
Metadata Date Stamp: 2010-01-08
Metadata Standard Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata Standard Version: FGDC-STD-001-1998