States Approve Water Quality Plan for Hells Canyon Hydro Projects

The certifications are a major milestone in the company’s pursuit of a new federal license to operate its largest source of electricity.

BOISE, Idaho — Idaho Power has taken a major step toward a new federal license for its largest hydroelectric project: Idaho and Oregon have certified the company’s plan for meeting water quality standards in the Snake River as part of its operation of three dams in Hells Canyon.

Section 401 of the federal Clean Water Act requires the company to produce a plan to meet state water quality standards as part of the relicensing process. Because Hells Canyon is on the Idaho–Oregon border, both states must approve the company’s plan (commonly called a 401 certification).

The plan’s acceptance, announced late Friday (May 24), is a significant move forward in the company’s application to relicense Brownlee, Oxbow and Hells Canyon dams. Together, those projects provide about 70% of the company’s hydroelectric generation and are the backbone of Idaho Power’s clean energy mix. The original license for the complex expired in 2005, and the company has operated the dams on a series of annual licenses since then.

Under the plan, Idaho Power commits to a wide range of water-quality improvement measures. Some have been developed and tested over the past several years, while others will be implemented when the company receives a new long-term license from the Federal Energy Regulatory Commission.

“Receiving the 401s from the states is a huge milestone for the company,” said Brett Dumas, Director of Environmental Affairs for Idaho Power. “This allows us to move forward with relicensing our most valuable asset. And, it clears the way for a tremendous number of projects to improve the environment of the Snake River while Idaho Power continues to provide safe, reliable, clean energy into the future.”

Idaho Power has proposed an extensive series of upstream river restoration measures, including the Snake River Stewardship Program, to address water temperatures in the Snake River.

One major component of the company’s plan includes projects to narrow and deepen key stretches of the Snake River between Walters Ferry and Homedale, which improves natural river function and habitat. Working with landowners, the company has begun planting thousands of native trees and shrubs along tributaries of the Snake River to provide shade. Both measures will help decrease water temperatures.

Additional steps include funding for improvements, such as pressurized sprinkler irrigation to reduce runoff from agricultural land, equipment to increase the oxygen in water released from Brownlee Dam and spillway modifications to minimize dissolved gases, which can harm fish.

The company has already launched a 10-year study of mercury levels in Brownlee and Hells Canyon reservoirs in coordination with the U.S. Geological Survey. The 401 plan also proposes lowering Brownlee Reservoir in unusually warm years to reduce water temperatures during downstream salmon spawning.

Both states accepted and reviewed public comments on the plan prior to approval. The cost of measures included in the plan is estimated to exceed $400 million over the term of the license, which the company anticipates will be 50 years.

Idaho Power began the relicensing process in the mid-1990s with discussions involving a wide range of interested groups including state and federal regulators. The next step in the process will be for the Federal Energy Regulatory Commission to update its environmental review that was completed in 2007.  Idaho Power expects to receive a new license in 2022.

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About Idaho Power

Idaho Power, headquartered in vibrant and fast-growing Boise, Idaho, has been a locally operated energy company since 1916. Today, it serves a 24,000-square-mile area in Idaho and Oregon. The company’s goal to provide 100-percent clean energy by 2045 builds on its long history as a clean-energy leader that provides reliable service at affordable prices. With 17 low-cost hydroelectric projects at the core of its diverse energy mix, Idaho Power’s residential, business and agricultural customers pay among the nation’s lowest prices for electricity. Its 2,000 employees proudly serve more than 560,000 customers with a culture of safety first, integrity always and respect for all.

IDACORP Inc. (NYSE: IDA), Idaho Power’s independent publicly traded parent company, is also headquartered in Boise, Idaho. To learn more, visit or

Brad Bowlin
Communications Specialist
Idaho Power