An official website of the United States government.

We've made some changes to If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

Effluent Guidelines

Steam Electric Power Generating Effluent Guidelines - 2015 Final Rule

EPA, on September 30, 2015, finalized a rule revising the regulations for the Steam Electric Power Generating category (40 CFR Part 423). The rule sets the first federal limits on the levels of toxic metals in wastewater that can be discharged from power plants, based on technology improvements in the steam electric power industry over the last three decades.
  • On an annual basis, the rule is projected to reduce the amount of toxic metals, nutrients, and other pollutants that steam electric power plants are allowed to discharge by 1.4 billion pounds and reduce water withdrawal by 57 billion gallons
  • Estimated annual compliance costs for the final rule are $480 million
  • Estimated benefits associated with the rule are $451 to $566 million

On this page:


Steam electric plant discharges include arsenic, lead, mercury, selenium, chromium, and cadmium. Many of these toxic pollutants, once in the environment, remain there for years.

The current regulations for the industry were last updated in 1982 and do not adequately address toxic metal discharges. The 1982 rule focused on settling out particulates rather than treating dissolved pollutants.

New technologies for generating electric power and the widespread implementation of air pollution controls over the last 30 years have altered existing wastewater streams or created new wastewater streams at many power plants, particularly coal-fired plants. The 2015 rule addresses these changes in the industry.


Affected Facilities

Illustration of key wastestreams at electric power plantKey Wastestreams - Click to enlargeCertain coal-fired steam electric power plants will be affected by this rule. EPA estimates that about 12 percent of steam electric power plants will incur some costs.

Regulatory Requirements

The final rule sets new or additional requirements for wastewater streams from the following processes and byproducts:
  • flue gas desulfurization
  • fly ash
  • bottom ash
  • flue gas mercury control
  • gasification of fuels such as coal and petroleum coke

Top of Page

Pending Litigation & Rule Reconsideration

EPA received multiple petitions for review challenging the regulations, which were consolidated in the U.S. Court of Appeals for the Fifth Circuit on December 8, 2015. The Agency later received petitions for administrative reconsideration of the final rule, in March and April 2017. EPA informed the petitioners that it will reconsider the rule. EPA also sent a letter to the states reminding them of flexibilities available to NPDES permitting authorities under the Final Rule. In light of the reconsideration, EPA views that it is appropriate to postpone impending deadlines as a temporary, stopgap measure to prevent the unnecessary expenditure of resources until it completes reconsideration of the 2015 rule.

EPA has proposed revisions for flue gas desulfurization (FGD) wastewater and for bottom ash (BA) transport water.

After reflecting on the time it typically takes the Agency to propose and finalize revised effluent limitations guidelines and standards, and in light of the characteristics of this industry and the anticipated scope of the next rulemaking, EPA projects that it will take approximately three years to propose and finalize a new rule (i.e., Fall 2020). Thus, EPA has finalized a rule postponing the earliest compliance dates for the BAT effluent limitations and PSES for BA transport water and FGD wastewater in the 2015 Rule, from November 1, 2018 to November 1, 2020.

Top of Page

Final Rule


Documents related to the rulemaking can be found on EPA’s docket at The Docket Number is EPA-HQ-OW-2009-0819.

Top of Page

Background Documents

Additional Information

For additional technical information about the final rule, please contact Ronald Jordan ( or 202-566-1003. For economic information please contact James Covington ( or 202-566-1034.

Top of Page