Regulatory Developments, Wastewater

EPA Proposes Stronger Wastewater Discharge Standards for Coal-Fired Power Plants

In March 2023, the EPA proposed strengthening wastewater discharge standards that apply to coal-fired power plants. The proposed rule would establish more stringent discharge standards for three wastewaters generated at coal-fired power plants:

  • Flue gas desulfurization wastewater
  • Bottom ash transport water
  • Combustion residual leachate

The proposed rule also addresses wastewater produced by coal-fired power plants that is stored in surface impoundments (for example, ash ponds). The proposal would define these “legacy” wastewaters and seeks comment on whether to develop more stringent discharge standards for these wastewaters.

The EPA is also proposing changes to specific compliance paths for certain “subcategories” of power plants. The Agency’s proposal would retain and refresh a compliance path for coal-fired power plants that commit to stop burning coal by 2028, and it’s issuing a direct final rule and parallel proposal to allow power plants to opt into this compliance path. Additionally, power plants that are in the process of complying with existing regulations and plan to stop burning coal by 2032 would be able to comply with the proposed rule.

Coal-fired power plants’ wastewater discharges include toxic and bioaccumulative pollutants such as:

  • Selenium
  • Mercury
  • Arsenic
  • Nickel
  • Halogen compounds such as:
    • Bromide
    • Chloride
    • Iodide
    • Nutrients
    • Total dissolved solids

These pollutants, which are discharged into U.S. waters, can contaminate drinking water sources, recreational waters, and aquatic life. In people, health risks may include cancer and non-cancer effects, and they may cause lower IQs in children. In fish and wildlife, the pollutants may cause deformities and reproductive harm. Many of these pollutants can remain in the environment for years.

Due to their close proximity to these discharges and relatively high consumption of fish, some minority and low-income communities have greater exposure to, and are at greater risk from, pollutants in steam electric power plant discharges.

The Steam Electric Power Generating Effluent Guidelines apply to a major portion of the electric power industry. These are plants that are primarily engaged in the generation of electricity for distribution and sale, which results primarily from a process utilizing fossil-type fuel or nuclear fuel in conjunction with a thermal cycle employing the steam water system as the thermodynamic medium. The EPA estimates there are approximately 914 of these facilities located throughout the United States.

The “EPA estimates that the proposed rule would reduce pollutants discharged through wastewater from coal-fired power plants by approximately 584 million pounds per year,” says an Agency news release.

The EPA is simultaneously publishing a direct final rule to extend the deadline for plants to opt into the 2028 early retirement provision promulgated in the 2020 regulation.


Effluent Limitations Guidelines (ELGs) are national industry-specific wastewater regulations based on the performance of demonstrated wastewater treatment technologies (also called “technology-based limits”). They are intended to represent the greatest pollutant reductions that are economically achievable for an entire industry.

In September 2015, the EPA finalized a rule revising the ELGs for the Steam Electric Power Generating category, setting the first federal limits on toxic metals in wastewater that can be discharged from power plants. In August 2020, the Agency finalized a “reconsideration” rule revising the 2015 requirements for FGD wastewater and BA transport water. The EPA reviewed the 2020 reconsideration rule in accordance with President Joe Biden’s Executive Order 13990 directing the Agency to review all regulations and policies undertaken by the previous administration and rescind or revise any that don’t protect public health and the environment. In July 2021, the EPA announced its intent to develop the rulemaking in this proposed rule.

Public comment and hearings

The EPA is accepting public comments on the proposal through May 30, 2023.  Comments can be submitted online at under Docket Number EPA-HQ-OW-2009-0819.

The Agency will conduct online public hearings on the proposed rule on April 20 and 25, 2023. Pre-registration is required either to provide testimony or to “listen only” to the hearings.

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