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Nonpoint Source Water Pollution

Nonpoint Source > Watershed Assessment > Water Quality Assessments and Reporting Water Quality Assessments and Reporting

The Indiana Department of Environmental Management (IDEM) develops the Integrated Water Monitoring and Assessment Report every two years to fulfill the requirements of Sections 305(b) and 303(d) of the federal Clean Water Act (CWA). The Integrated Report is submitted to U.S. EPA in even-numbered years.

The Integrated Report (as it is commonly called) is a narrative report that provides information on IDEM’s CWA programs and other programs at IDEM that work together to protect and restore Indiana waters. The Integrated Report also provides statewide summaries and waterbody-specific information on the degree to which Indiana waters are supporting their designated beneficial uses identified in the state’s Water Quality Standards (WQS).

The summary and water-body-specific information in the report comes from the water quality assessments that IDEM conducts to meet the CWA Section 305(b) requirement to assess and report on the degree to which Indiana waters support their designated beneficial uses. These assessments are made in accordance with IDEM’s Consolidated Assessment and Listing Methodology (CALM) by comparing existing and readily available water quality data to the applicable water quality criteria in the State’s water quality standards.

CWA Section 303(d) requires states to identify waters that are not meeting applicable water quality standards and as a result, are not fully supporting one or more of their designated beneficial uses. These waters are considered by IDEM to be impaired and must be placed on the Indiana’s 303(d) List of Impaired Waters.

Section 303(d) also requires state to develop Total Maximum Daily Loads (TMDLs) for the waters identified on the 303(d) list. TMDLs are reports that provide an overview of one or more impaired waters, and identify:

  • the sources of pollutants impacting them
  • the methods used to analyze data
  • the reductions in levels of pollutants needed to restore water quality
  • the actions that need to be taken to reduce pollutant levels
  • any actions that are currently being taken to improve water quality

The 303(d) list is a subset of the Consolidated List, which provides water quality information for most of the surface waters throughout the state. For the Consolidated List, IDEM places each waterbody into one or more categories based on what is known about its water quality and the degree to which it is supporting its designated beneficial uses:

  • Category 1: All designated beneficial uses for the waterbody are supported and no use is threatened.
  • Category 2: The available data and or other information indicate that some, but not all of the waterbody’s designated beneficial are supported and no use(s) are impaired or threatened.
  • Category 3: There is insufficient data and or other information available to determine if the waterbody is supporting a given designated beneficial use.
  • Category 4: The available data and or information indicate that a designated beneficial use is impaired or threatened but a TMDL is not required because:
    1. A TMDL has already been completed for the impairment(s) and approved by U.S. EPA and is expected to result in attainment of all applicable water quality standards;
    2. Other pollution control requirements are reasonably expected to result in the attainment of applicable water quality standards in a reasonable period of time; and/or,
    3. Impairment is not caused by a pollutant for which a TMDL can be calculated.
  • Category 5: The designated beneficial use is impaired, and a TMDL is required because:
    1. The waterbody is not supporting aquatic life use, recreational uses, or drinking water use (if so designated) and is impaired or threatened by one or more pollutant(s);
    2. The “fishable use” of the waterbody is impaired because the concentration of mercury or PCBs in the edible tissue of fish collected from the waterbody exceeds Indiana’s human health criteria for these contaminants.

The most current Integrated Report and 303(d) list and the CALM used for their development can be found online:

Electronic Services

  • Impaired Waters (e303d):
    • This web-GIS application provides a display of the impaired waters along with additional information associated with the listings, such as the development status of TMDLs and the establishment of watershed management plans (WMPs). This application offers users the ability to zoom to their address, water body, county, or watershed, identify waterbodies and all associated listing category data, TMDLs and WMPs where these activities are or have been occurring in the selected area, and provides the assessments reported in the Integrated Report. You may also skip the tutorial page.

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