Cooling Water Intake Structure

Photo: Cooling Water Intake Structure
Illustration of cooling water intake structures

Columbia Generating Station gets its cooling water from the Columbia River “through two 42-inch diameter intake structures (pictured on the right) perforated with 3/8 inch diameter holes, each approximately 20 feet long and placed parallel to river flow approximately 350 feet offshore at low water. 

Water flows by gravity to the River Pumphouse. The intake structures for CGS were designed and constructed in the late 1970s.” 

The intakes were designed “to minimize the impact of make-up water from the Columbia River, with particular emphasis on salmonid fry.”

How do we know this? Two studies that were conducted, both pre- and post-operational.

In the 1985 study the monitoring program looked at both impingement and entrainment between April and September. No juvenile salmonids were found to be affected. This monitoring program was undertaken with study-plan review by the National Marine Fisheries Service.

The Circulating Water System consists of the CW Basin, three CW pumps, six mechanical draft cooling towers, and the necessary valves, piping, controls and instrumentation to continuously transport heat from the Main Condenser to the atmosphere.

The Role of the NMFS

The NMFS opinion on our intake structure has been found to be without merit twice (the first time being Columbia’s license renewal where the Nuclear Regulatory Commission found their argument uncompelling).

In part this is because the NMFS design criteria for intake structures pertains to models not utilized by Columbia Generating Station. As Dr. Charles Coutant wrote in his discussion paper prepared for a meeting with the agency in 2013: “NMFS does not have design criteria specifically for cylindrical screens oriented parallel with the current in flowing water...”

Still, EFSEC wanted to address the NMFS concerns. So in the permit issued in 2014, a new study was undertaken in 2018-2019 to update the entrainment data from the 1985 study that found zero impact on fish. The final report was submitted Feb. 26, 2020 and found very low impact on fish. 

The EPA and Cooling Water Intakes

The Environmental Protection Agency issued its final rule (316b) regarding cooling water intakes for existing power plants in May, 2014. The rule is designed to better protect fish and aquatic life in all bodies of water.

From the EPA news release:
“Existing facilities that withdraw at least 25 percent of their water from an adjacent waterbody exclusively for cooling purposes and have a design intake flow of greater than 2 million gallons per day are required to reduce fish impingement. To ensure flexibility, the owner or operator of the facility will be able to choose one of seven options for meeting best technology available requirements for reducing impingement.”

Key Documents:

Columbia Generating Station’s NPDES Permit Amendment No. 2

Columbia’s NPDES permit Fact Sheet - PDF Format



​Who is EFSEC?

The State of Washington Energy Facility Site Evaluation Council  provides a "one-stop" siting process for major energy facilities in the State of Washington.  Learn more about EFSEC