TMDL

Total Maximum Daily Load  (TMDL) Program

Louisiana New Vision Program - click the link for more information

Louisiana TMDL Process Information

• Permitting Implementation Plan for Bayou Lacombe (Subsegments 040901, 040902) Phase I Dissolved Oxygen TMDL

• Permitting Implementation Plan for the DRAFT Lower Tchefuncte River DO TMDL (Subsegments 040802 and 040803)

• Permitting Implementation Plan for Bayou Bonfouca/Bayou Liberty Phase 1 DO TMDL (Subsegments 040905, 040906, 040907, 040908)

• Permitting Implementation Plan for Colyell Creek Phase 1 DO TMDL (Subsegment 040305)

• Permitting Implementation Plan for Selsers Creek Phase 1 DO TMDL (Subsegment 040603)

• Permitting Implementation Plan for Lower Amite River DO TMDL (Subsegment 040303)

• Permitting Implementation Plan for Bayou Cane DO TMDL (Subsegments 040903 and 040904)

• LDEQ's Approach to Dissolved Oxygen TMDL's for Pontchartrain Basin Waterbodies

TMDL Water Quality Modeling

• TMDL Program Brochure

• LDEQ Developed TMDL Reports and Models for Louisiana

  • Louisiana TMDL Technical Procedures

  • Louisiana's LAQUAL Model and Users Manual (zip file)

  • LACOULEE Single-branch Water Quality Model

  • Louisiana's Water Quality Management Plan - Volume 8 (updated 01/12/2023)

• Ultimate Biochemical Oxygen Demand Analysis

• Water Quality Surveys for TMDL Development

  • The Water Surveys Section was initally created as a part of the TMDL Program, sponsored by the Environmental Protection Agency (EPA). In 1972, the "Clean Water Act", developed by the EPA, implemented pollution control programs such as settling water quality standards for all contaminants in surface waters. Total Maximum Daily Load (TMDL) is the amount of a pollutant a waterbody can assimilate without exceeding the established water quality standard for that pollutant. The Water Survey Section performs intensive surveys on impaired waterbodies of Louisiana, which are listed on the EPA's 303(d) list.

    During a survey on a watershed, a wide range of biological, physical and chemical data is collected by Environmental Scientists then evaluated by DEQ's modelers. Environmental Scientists employ several methods of collecting data such as time-of-travel, stream geometry, water quality, disharges, reaeration, stream flow, etc. Assessment of data may eventually result in revisions in the water quality standards set or a delisting of a waterbody deemed to be meeting current standards.

Ambient Water Quality Data

The Louisiana Department of Environmental Quality collects ambient surface water data at approximately 125 sites across the state each month. This data is used for establishing water quality criteria or standards, assessment of conditions, and development of Total Maximum Daily Loads (TMDLs). TMDLs are one means of establishing water quality discharge permit limits and Nonpoint Source Pollution reduction recommendations for the protection and improvement of surface water quality in Louisiana.

Over 600 monitoring sites have been established since 1958 but not all sites are currently in use. Data has been collected at some of these sites since the inception of the program; however, most sites were established more recently. In 1998 the department established a rotating basins monitoring program in order to expand the coverage of our monitoring efforts. Under this plan approximately 100 sites are selected each year for monitoring once a month. In addition, 21 sites on 16 water bodies are monitored every month of every year as long-term trend sites.

The public may also obtain the data by contacting Public Records. Please provide Public Records with site numbers obtained from Ambient Water Quality Monitoring Sites and parameters of interest from Ambient Water Quality Parameters.  For questions regarding Louisiana's ambient water quality monitoring program please contact the Water Planning and Assessment Division, Water Quality Standards and Assessment section.

Ambient Water Quality Data online query tool

TMDL Public Participation

Click here to subscribe to electronic notification of LDEQ TMDL or 305(b)/303(d) updates or changes or visit LDEQ's Pubic Notices page here: Public Notices

USEPA TMDL Information

• Subscribe to electronic notification of USEPA's Water Federal Register updates (includes TMDLs and all water-related issues nationwide)

• Consolidated Assessment and Listing Methodology Guidance (CALM)

• EPA's Integrated Water Quality Monitoring and Assessment Guidance for 303(d) and 305(b) Reporting

• EPA Region 6: TMDL Reports and Information

• EPA Region 6: Water Quality Protection Division

• EPA TMDL Program

• EPA Office of Water

• EPA How's My Waterway?

  How's My Waterway was developed by EPA to display assessment data for all 50 states. Since states may assess waterbodies in different ways, the underlying assessment information is the same as LDEQs currently approved IR but may be displayed in a different manner. The tool allows the public to search EPA's ATTAINS database, which is populated by LDEQ and other state agencies, for water quality information pertaining to their community. The information contained in How's My Waterway, does not supersede LDEQ's own assessment information found in the preceding links. For more information on How's My Waterway look for the "About" icon at the EPA site.

Other Helpful Links

• LSU School of the Coast and Environment

• LUMCON - Louisiana Universities Marine Consortium

• US Army Corps of Engineers - Coastal Hydraulics Laboratory

• US Geological Survey - "Science in Your Watershed"