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Wastewater from Coal-Fired Power Plants: EPA’s Proposed Rules



March 13, 2023 - The EPA is proposing to strengthen the wastewater discharge standards that apply to coal-fired power plants. The agency’s proposal addresses discharges of toxic metals and other pollutants into water bodies. 

Three Wastewaters and Related Toxics Targeted

The proposed rule amends the rules adopted in 2020 and establishes more stringent discharge standards for three wastewaters:

  1. Flue gas desulfurization wastewater;
  2. Bottom ash transport water; and
  3. Combustion residual leachate.

The proposal would also establish a new set of definitions for various legacy wastewaters, which may be present in surface impoundments prior to more stringent limitations in a discharge permit going into effect.

The toxics and bioaccumulative pollutants that are the target of the rule include selenium, mercury, arsenic, and nickel, halogen compounds such as bromide, chloride, and iodide, nutrients, and total dissolved solids.

The EPA’s Fact Sheet outlines the history of the “technology-based” effluent guidelines for the Steam Electric Power Generating category that apply to power plants that generate electricity through the creation of steam. The proposed rule focuses on a subset of steam electric plants that burn coal to create steam and amends EPA’s earlier updates to the effluent limit guidelines for this category that were promulgated in 2015 and in 2020.

Less Stringent BAT Requirements Eliminated

For existing sources that discharge directly to surface water, with the exception of certain identified subcategories, the proposed rule establishes effluent limitations based on Best Available Technology Economically Achievable (BAT).  However, the proposed rule would eliminate the separate, less stringent BAT requirements for two subcategories: high flow facilities and low utilization electric generating units (LUEGUs).

Implementation Flexibilities

The proposed rule includes implementation flexibilities that acknowledge, for example, that some plants have installed, or are in the process of installing, additional treatment technologies to meet the 2015 and 2020 regulations. The rule would allow additional time for these plants to come into compliance with the revised rule. In addition, recognizing that some coal-fired power plants are in the process of closing or switching to less polluting fuels such as natural gas, the rule includes flexibilities to allow these plants to continue to meet the 2015 and 2020 regulation requirements rather than the new rule.

Direct Final Rule

EPA is simultaneously publishing a direct final regulation to extend the deadline for plants to opt-in to the 2028 early retirement subcategory promulgated in the 2020 regulation. The opt-n period had expired in 2022, but EPA acknowledges that additional plants would choose to opt-in to this subcategory if additional time to do so were granted. The direct final regulation would extend the period to opt-in to this subcategory.

EPA will conduct public hearings on the proposed rule on April 20 and 25, 2023.

This post was drafted by John Watson, an attorney in the Denver, Colorado office of Spencer Fane LLP. For more information, visit