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Total Maximum Daily Load Program: Communities Working Together to Improve Water Quality

The TMDL program works with communities to take care of Texas by improving the quality of their streams, lakes, and bays through development of total maximum daily loads (TMDLs) and their implementation plans (I-Plans).

A Total Maximum Daily Load is a scientifically-derived target for water quality that tells us the greatest amount of a particular substance that can be added to a water body without compromising its health. The TMDL gives us a measurable goal to protect and improve the quality of our streams, lakes, and bays.

Substances considered in a TMDL are not necessarily harmful in and of themselves. For example, phosphorus is an essential nutrient, but too much phosphorus can lead to an overgrowth of algae. Another example is bacteria, which occur naturally in both human and animal waste. But too much bacteria can make it more hazardous to swim in a creek, lake, or bay—activities called “contact recreation” in the state’s standards for water quality.

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TMDL Projects

Projects of the TMDL Program

Find impaired or threatened water bodies where the TMDL program is protecting people and aquatic species by reducing pollution.

TMDLs and their Implementation

Learn what a TMDL is and how TCEQ and stakeholders make a difference in the quality of our water bodies.

Developing TMDL Projects

Read guidelines for organizations that develop or implement TMDLs in Texas.

Get Involved


Read the latest about TMDLs, I-Plans, and water quality.


Learn about upcoming stakeholder meetings.

Participating in TMDL Projects

Get involved in your watershed.

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Receive e-mail or text updates from the Total Maximum Daily Load program

Impaired Waters and TMDLs

All Impaired Waters, 2022

Review a list of water bodies with Category 4- and 5 impairments in the EPA-approved Texas Integrated Report of Surface Water Quality.

Summary of Completed TMDLs and I-Plans

After a TMDL is complete, I-Plan development or approval may be incomplete. The list includes dates of adoption or approval by the commission and EPA.


Preserving and Improving Water Quality

Read an overview of how TCEQ defines, measures, evaluates, and manages the quality of surface waters in Texas.

Watershed Action Planning

Review strategies and plans for protecting and improving the quality of the state's streams, lakes, and estuaries.

Hydrography Data and Map-Based Data Viewers

Access GIS-based data viewers and GIS data for classified segments and other surface water information.

For More Information

Please email or call us at 512-239-6682.

communities working together taking care of our rivers, lakes, and bays