Cooling Tower Recirculation Water

​​​​Columbia Generating Station produces a tremendous amount of energy from water that is boiled to make steam. To make that happen, there are two separate closed-loop systems at work – reactor recirculation water and cooling tower recirculation water.

The steam generated from the reactor recirculation system is turned back into water after passing through our steam condenser, a giant heat exchanger, which operates utilizing the cooling tower recirculation water system.

Cooling water from the Columbia River carries the heat from the condenser to six mechanical draft cooling towers where it is dissipated into the atmosphere as water vapor. This is known as a “closed-loop” or “closed-cycle” cooling system.

Circulating Water System chemistry is controlled to minimize algae growth, scaling and general corrosion. Other chemical additives are used to increase the effectiveness of chlorination, to act as a silt dispersant, and to introduce corrosion inhibitors into the raw water.

Water Quality in the Columbia

Columbia Generating Station has no effect on the Columbia River.

Columbia Generating Station uses about 24 million gallons of water from the Columbia River each day for cooling. About 1,700 gallons a minute, or 1.872 million gallons a day, are returned to the river. About 35 - 40 million gallons of water pass by our discharge point every minute. (After the Snake and Columbia join together, about 85 million gallons flow past The Dalles every minute).

What’s in the water we return to the river?

Energy Northwest prepares a monthly Discharge Monitoring Report to EFSEC that certifies all the water returned to the river was in accordance with the site National Pollution Discharge Elimination System (NPDES) permit. The permit requires pH levels to be within limits and halogens near undetectable at less than or equal to 0.1 micrograms per liter. Energy Northwest also monitors copper, chromium and zinc as a condition of the permit. The acceptable levels for chromium are 8.2 micrograms/liter and 53 micrograms/liter for zinc, while copper does not have a limit. The existing permit set a zero standard for PCBs and a non-detection standard for 126 priority pollutants. (Note: chromium and zinc are already present in the Columbia River).

Energy Northwest remains in full compliance with all environmental regulations related to our circulating water discharge.​

Key Documents:

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​​Who is EFSEC?

The State of Washington Energy Facility Site Evaluation Council (EFSEC or Council) provides a "one-stop" siting process for major energy facilities in the State of Washington. EFSEC coordinates all evaluation and licensing steps for siting certain energy facilities in Washington. EFSEC specifies the conditions of construction and operation. If approved, a Site Certification Agreement is issued in lieu of any other individual state or local agency permits. EFSEC also manages an environmental and safety oversight program of facility and site operations. Learn more about EFSEC