Current Draft TMDL Public Notices are posted above.
TMDL Program
DEQ manages the Total Maximum Daily Load (TMDL) program for the State of Oklahoma. A TMDL is the process of establishing the sources of impairment in a given waterbody, whether from point sources (discharges) or non-point sources (runoff), determining the amount of reduction necessary to meet water quality standards in that waterbody, and allocating the loads to the various contributors of pollution. A margin of safety is also included in the TMDL calculation process.
Water quality modeling is the linkage between the sources of pollution and the instream water quality of a given waterbody. A model is a representation of the water-quality processes that occur in a given waterbody. Water quality modeling can be resource-intensive. Different levels of complexity may be used depending on the level of confidence required in a given situation.
Red-Sulphur Subregion Study Area Draft Bacteria and Turbidity TMDL Report and Public Notice
Please submit comments in writing to: Soojung Lim, Water Quality Division, Oklahoma Department of Environmental Quality, PO Box 1677, Oklahoma City, OK 73101-1677
or by email at Water.Comments@deq.ok.gov
Southeast Oklahoma Draft Bacteria and Turbidity TMDL Report and Public Notice
Please submit comments in writing to: Soojung Lim, Water Quality Division, Oklahoma Department of Environmental Quality, PO Box 1677, Oklahoma City, OK 73101-1677
or by email at Water.Comments@deq.ok.gov
Arkansas – Keystone Basin Study Area Draft Bacterial TMDL Report and Public Notice
Please submit comments in writing to: Soojung Lim, Water Quality Division, Oklahoma Department of Environmental Quality, PO Box 1677, Oklahoma City, OK 73101-1677
or by email at Water.Comments@deq.ok.gov
- Public Notice for the Arkansas – Keystone Basin Bacterial TMDL – Comment period closes June 20, 2025
- Arkansas – Keystone Basin Draft TMDL Report
- Arkansas – Keystone Basin Draft TMDL 208 Fact Sheet
Neosho and Verdigris Basins Bacterial and Turbidity Draft TMDL Report and Public Notice
Please submit comments in writing to: Tamara Scott, Water Quality Division, Oklahoma Department of Environmental Quality, PO Box 1677, Oklahoma City, OK 73101-1677
or by email at Water.Comments@deq.ok.gov
Lake Oologah TMDL Report
- Public Notice for the Lake Oologah Draft TMDL
- Lake Oologah Draft TMDL Report
- Appendix A – Data Acquisition and Assessment
- Appendix B – Watershed Model Calibration and Validation Report
- Appendix C – EFDC Hydrodynamic and Water Quality Model
- Appendix D – Oklahoma Antidegradation Policy
- Appendix E – Water Withdrawals in Verdigris River Basin
- Appendix F – Sanitary Sewer Overflow Bypass Events
- Appendix G – Stream Flow Data
- Appendix H – NPDES Data
- Appendix I – Ambient Monitoring Data at Watershed and Lake Stations
- Appendix J – Stormwater Permitting and BMPs
- Lake Oologah 208 Factsheet
Fort Gibson Lake TMDL Report
- Public Notice for the Fort Gibson Lake Draft TMDL
- Fort Gibson Lake TMDL – EPA Approval Letter
- Fort Gibson Lake Draft TMDL Report
- Appendix A – HSPF Watershed Model
- Appendix B – EFDC Model
- Appendix C – Antidegradation Policy
- Appendix D – Ambient Monitoring Data
- Appendix E – Stormwater Permitting and BMPs
- Appendix F – SSO Bypass Events
- Appendix G – Stream Flow Data
- Appendix H – NPDES Data
- Appendix I – Distributions for Maximum Daily Loads
- Fort Gibson Lake 208 Factsheet
EPA approved TMDLs for the State of Oklahoma are available for viewing or download at the following web page:
Lake Thunderbird TMDLs for Nutrients, Turbidity, and Dissolved Oxygen received EPA approval on November 13, 2013. Documents and information related to development of the Lake Thunderbird TMDL can be found on the Lake Thunderbird TMDL Project Page.
Water Quality Monitoring – Surface water quality data is collected by State, federal, and local agencies.
Waterbody Assessment – Analysis of water quality data to determine if a waterbody is achieving water quality standards
303(d) List of Impaired Waterbodies – Waterbodies in the State of Oklahoma that do not meet water quality standards are compiled in the State’s 303(d) list.
TMDL Prioritization – DEQ prioritizes watersheds containing impaired waterbodies for TMDL development. A rating system is utilized to determine a priority ranking value for each impaired watershed.
TMDL Development – A Total Maximum Daily Load value for each cause of impairment in a waterbody is calculated using appropriate water quality models.
Public Review – TMDL reports are published for public review and comment. DEQ accepts any comments submitted during the specified review period.
Report submittal – DEQ submits the TMDL report to EPA for review and approval.
EPA approval – EPA approves the TMDL report if the TMDL calculations are technically sound and the report satisfies required elements.
DEQ employs the use of a number of different types of surface water quality modeling software. Model selection is based on the needs and complexity of a given project.
- Load Duration Curves – Simple
- QUAL2K – Stream and river water quality model developed at Tufts University for EPA
- SWAT – Soil & Water Assessment Tool
- LOADEST – Load Estimator software developed by USGS
- HSPF – Hydrological Simulation Program – FORTRAN
- BATHTUB – One-dimensional steady-state lake model
- EFDC – Environmental Fluid Dynamics Code
- ELCOM-CAEDYM – Estuary, Lake and Coastal Ocean Model – Computational Aquatic Ecostystem DYnamics Model
Contact Watershed Planning
Last Modified on
Sep 05, 2025
