MDEQ Impaired Waters & TMDL Tool
Why It's Important
To protect Mississippi’s water resources, the Mississippi Department of Environmental Quality (MDEQ) identifies and studies water bodies that don’t meet state water quality standards. The agency determines how much pollution a water body can handle—called a Total Maximum Daily Load (TMDL)—to guide restoration and ensure long-term water quality. GIS innovation helps to monitor this data and share it with the public.
The TDML Tool
The TMDL Tool is an interactive, map-based resource developed by the Geospatial Group for MDEQ to help identify all waters affected by activities at a specific location. Section 303(d) of the Clean Water Act requires states to identify all water bodies that do not meet state water quality standards; Built on the framework of this act, the tool brings together water quality data, watershed boundaries, and relevant reports—such as TMDL reports, 303(d) impairment listings, and EPA waterbody summaries. This tool supports MDEQ staff, engineers, and the public in understanding how land use and watershed activities influence water quality and regulatory requirements.
Impaired Waters
Waters impaired by a pollutant are included in the state’s Section 303(d) list as Impaired Waters. For these waters, the state must calculate how much of a pollutant can be added to these waters without violating the standard. That quantity is reported as a TMDL, which includes pollutant levels from point and non-point sources, plus a safety factor to maintain the integrity of the water. Limits may be set on pollutants entering water bodies, or serve as planning tools for improving water quality. MDEQ designs TMDLs so that impaired water bodies will meet and continue to meet state water quality standards. As a result, there are waters that are "impaired" but awaiting TMDL development, and waters where the TMDL has been calculated (considered TMDL complete waters).
User Interface
Efficient Transparency
The TMDL Tool was developed to share all waters affected by a location along with the pertinent TMDL report or Impairment Status. All TMDL Complete Waters and Impaired Waters must have a watershed, so our staff compiled/delineated these for each waterbody, and organized/cataloged all corresponding TMDL reports. ESRI's ArcGIS Desktop and
The TMDL Tool was developed to share all waters affected by a location along with the pertinent TMDL report or Impairment Status. All TMDL Complete Waters and Impaired Waters must have a watershed, so our staff compiled/delineated these for each waterbody, and organized/cataloged all corresponding TMDL reports. ESRI's ArcGIS Desktop and ArcGIS Online were utilized to create a simple online tool to provide quick and easy access to the information. Current TMDL engineers as wells as other MDEQ personnel and the public use the tool to see all waters affected by a location along with the corresponding TMDL Report, 303(d) Report, and EPA's Waterbody Report.
Search Functionality
The search function at the top of the tool offers several unique ways to locate information quickly and efficiently. Users can search by the name of a stream, town, or facility, and a list of matching suggestions will appear for easy selection. Searching by Water Body ID is also supported; these IDs may be entirely numeric or alphanumer
The search function at the top of the tool offers several unique ways to locate information quickly and efficiently. Users can search by the name of a stream, town, or facility, and a list of matching suggestions will appear for easy selection. Searching by Water Body ID is also supported; these IDs may be entirely numeric or alphanumeric (typically starting with “MS”). Additionally, users can search by Permit Number or Agency Interest Number. For those focused on specific contaminants, the tool also allows searches by pollutant (referred to by the EPA as a “Parameter”). Entering the pollutant name will return a list of all water bodies with a completed TMDL for that parameter. These versatile options ensure users can access exactly the data they need with ease.
Convenient Resources
Convenient Resources
When a location is selected within the TMDL Tool, a pop-up box appears displaying key information about that area, including links to relevant MDEQ TMDL reports, EPA waterbody summaries, and other related resources. This feature provides users with direct access to detailed data and documentation about water bodies and watershed features
When a location is selected within the TMDL Tool, a pop-up box appears displaying key information about that area, including links to relevant MDEQ TMDL reports, EPA waterbody summaries, and other related resources. This feature provides users with direct access to detailed data and documentation about water bodies and watershed features affected by or associated with the selected location, making it easier to explore and understand water quality conditions and regulatory information with just a few clicks.