Total Maximum Daily Load (TMDL)

In 1996, the Texas Commission on Environmental Quality (TCEQ) first identified waterways in the Houston region as having bacteria levels high enough to raise concerns about whether the identified waterways are safe for swimming and wading. These waterways were listed in the state’s “303(d) List,” which identifies waterways that do not meet state standards for various uses.

Since then, TCEQ has studied these and other waterways more thoroughly to discover the extent of the high levels of bacteria. As a result, additional waterways have been listed as impaired. The TCEQ developed Total Maximum Daily Loads, or TMDLs, for these waterways. TMDLs are like a budget for pollution: they quantify how much of a pollutant a waterway can absorb and still meet state standards and they identify how much of a reduction is required to meet the state standard.

After the TMDL budget is established, an implementation plan is drawn up, which details steps needed to reduce bacteria to safe levels. Because the people, resources, and solutions for the implementation plans for these TMDLs have so many similarities, stakeholders from the TMDL projects agreed that a combined group to develop the implementation plan would be appropriate.