TMDLs and the protection of waterways

Date Posted: 12/19/2022

Total Maximum Daily Loads (TMDLs) are action plans to restore clean water. They are a calculation of the maximum amount of a pollutant allowed to enter a waterbody so that the waterbody will meet and continue to meet water quality standards for that pollutant. Section 303(d) of the Clean Water Act (CWA) requires that states identify waterways that do not meet water quality standards and the pollutants that damage them.

A TMDL equation adds together the sum of point sources, the sum of nonpoint sources and background, and the margin of safety (MOS). The MOS accounts for uncertainty in predicting how well pollutant reductions will meet water quality standards.

Once a state submits TMDLs, the Environmental Protection Agency (EPA) reviews and approves or disapproves. After the TMDL is approved by EPA, TMDL point source allocations are usually implemented through National Pollutant Discharge Elimination System permits under CWA section 402. 

Over the last few decades, EPA scientists and collaborators measured increases in salt concentration in nine bodies of water around urban areas. Results found that increasing freshwater salinization is a wide-spread problem in the United States and worldwide.

Even though freshwater has natural salts, too much salt can harm aquatic life. Human activities can contribute to the increase, including:

  • Road salt application,
  • Water softening,
  • Mining and oil production, and
  • Other commercial and industrial processes.

EPA outlined strategies to address this issue, one of which ties back into TMDLS. Chloride is one of the many types of salts that contribute to this freshwater salt increase. States are encouraged to develop TMDLs for chloride. Some already are, since they recognize the complications related to the salt. If more states opted to develop TMDLs for chloride, there may be noticeable improvements in freshwater salinization nationwide. Some other strategies to tackle increasing salt concentrations in freshwater include:

  • Process changes with agricultural sources to keep salts out of waterways to begin with; and
  • Regular training for vehicle operators on the best ways to apply salt to roadways efficiently.

How Safety Management Suite Can Help

Staying in compliance with federal environmental regulations is challenging, especially when new variables are being introduced. The J. J. Keller® SAFETY MANAGEMENT SUITE offers ezExplanations to help summarize water permitting requirements and further explain Total Maximum Daily Loads. The service also offers the ability to ask TMDL-related questions through the Expert Help tool. The Subject Matter Experts who support the SAFETY MANAGEMENT SUITE will provide a response within one business day.

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