Clean Water Act Section 316(b): Cooling Water Intake


A majority of the world’s electricity is generated by steam turbines driving electric generators at power plants. A single turbine can generate an immense amount of electricity using heat to generate steam and water for cooling. At most facilities, cooling water is withdrawn from rivers, oceans and lakes, and then returned to the water body. Under Section 316(b) of the Clean Water Act, the U.S. Environmental Protection Agency (EPA) requires most power plants to identify and implement the best methods for reducing potential impacts to aquatic life related to the withdrawal of cooling water.

The EPA’s final Section 316(b) regulations for existing facilities became effective in October 2014. These regulations are intended to reduce the mortality of aquatic life due to the impingement of organisms on cooling water intake screens and the entrainment of smaller organisms through the screens into the cooling system. The rule contains the following requirements for facilities that have a design intake flow of greater than 2 million gallons per day (MGD) of which more than 25 percent is used for cooling.

The rule requires all affected facilities to submit a number of reports that describe the facility and the source water, and propose measures to be compliant with the rule’s requirements. The studies must be submitted with a facility’s permit renewal application under the National Pollutant Discharge Elimination System (NPDES) program, or on an alternative schedule agreed to with the permitting agency.

How it affects Great River Energy

The rule will affect Great River Energy’s Elk River Energy Recovery Station which uses water withdrawn from the Mississippi River in Elk River, Minn., and Coal Creek Station (CCS) which uses water from the Missouri River in North Dakota for a closed-cycle cooling system. The precise nature of the compliance requirements for each facility will be determined after further study and discussion with the regulating agency.

CCS does not hold an industrial wastewater discharge permit since it is a zero liquid discharge facility. Nevertheless, for the sole purpose of compliance with the 316(b) rule, CCS has applied for an NPDES permit. No new requirements are expected from the yet-to-be-issued permit since CCS’s cooling water intake structure is compliant with 316(b) requirements.

In 2014, Elk River Energy Recovery Station submitted a complete and timely NPDES permit renewal application to the Minnesota Pollution Control Agency (MPCA). The timing to conduct the required set of studies is dependent on the MPCA’s issuance of the permit renewal and the schedule outlined by the agency therein.

June 12, 2017

Download a PDF of Great River Energy’s 316(b) Position Statement