11 Miss. Code. R. 6-9.5
The impaired waters in Tables 3-5 below are sorted alphabetically by the river basin then by the water body name. The extent of the segment is described beginning with the upstream boundary thence to the downstream boundary. The maps of these segments are located in Appendix A.
The pollutants are listed specifically for each listing. There are 241 listings for 2024. Biological Impairment is listed 223 times (92.5%). This listing is generated based on assessing the result of our benthic sampling program M-BISQ.
When the water body is scored below the eco-regional value, it is added to the impaired waters list. A stressor identification process is then used to identify the specific pollutants causing the microbiological impairment. Organic Enrichment, Total Nitrogen, and Total Phosphorus listings are for excessive nutrients or organics which impact the dissolved oxygen and eutrophication in the water body. The pH listings are from water monitoring results which are outside of the water quality criteria for pH. If there are multiple pollutants and/or uses for a water body, these are shown as multiple listings for the water body.
Due to the nature of the monitoring and listings for 2024, the source of the impairment is generally not known. For the biological listings a stressor identification process is required to identify probable primary stressors. Once identified, these probable primary stressors are incorporated into the §303(d) List and the biological impairment listing is removed.
MDEQ and USGS completed work on the new 12-digit watershed-based delineation of Mississippi in 2005. MDEQ incorporated this new delineation into the identification numbering system for water body segments in the states beginning with the 2006 §305(b) report. Each listed water body segment is identified by a six-digit numeric code. The first digit identifies which basin contains the water body. The major river basins are numbered 1 through 9 in alphabetical order (1 for the Big Black River Basin, 2 for the Coastal Streams Basin, through 9 for the Yazoo Basin.) [See map on page 4.] The next three digits in the six-digit water body identification number refer to the specific subwatershed within that basin. Each major river basin has the subwatersheds it contains numbered beginning with 1 (subwatershed 146 located in the Big Black River Basin would be numbered 1146, subwatershed 74 located in the Pascagoula River Basin would be numbered 4074.) The final two digits in the six-digit water body identification number refer to a specific stream segment within the specified subwatershed. For instance, Beaver Creek, water body ID 521413, is stream segment 13 in subwatershed 214 in the Pearl River Basin.
Maps are included in Appendix A for each basin. Streams shown in blue are the impaired stream segments. In some river basins, the maps were split into 8-digit Hydrologic Unit Codes to better fit the page.
11 Miss. Code. R. 6-9.5