BOISE — A proposal to raise seasonal minimum outflows from Hells Canyon Dam aims to benefit Snake River downstream uses such as recreation and fisheries.

But the idea raises concerns from Idaho Power Co.

The non-binding Idaho House Joint Memorial 9 calls on the Federal Energy Regulatory Commission to raise the minimum outflow to 8,500 cubic feet per second from May 15 to Oct. 1 at or below Hells Canyon Dam. That would reduce major fluctuations in stream levels and improve fisheries and river navigation to the benefit of the economically significant recreation industry, according to the memorial’s purpose statement.

Idaho Power in a normal water year gets about 30% of the total energy it generates from the Hells Canyon complex. The complex includes the Brownlee, Oxbow and Hells Canyon dams.

Idaho Power owns the complex. Its FERC operating license requires a 5,000 cfs minimum flow, and its proposed new license would increase that to 6,500 cfs except in atypical conditions, when 5,000 would be permitted, company spokesman Brad Bowlin said.

The Idaho State Water Plan sets minimums of 4,750 cfs at Weiser and 5,000 at Johnson Bar, downstream of Hells Canyon Dam.

“So it is possible that, if the state was operating at or near those minimums, we would only have 5,000 cfs coming into Brownlee, so we would not be able to sustain outflows greater than that,” Bowlin said. Flows have not been that low at Johnson Bar for more than 30 years, “so it’s not a likely scenario.”

Ideally, inflows and outflows balance to the extent Idaho Power retains flexibility, he said. This helps the company supply power when demand is high and cover a temporary loss of another generation system or transmission line.

High outflows generate more power, “but the other side is that there are times when we need to hold that water back so that we have it available for later,” Bowlin said. When demand remains high on a late-summer day as solar generation drops, “we need to have that water available to crank up the generators and generate more electricity.”

A study by Idaho Power found that an 8,500 cfs seasonal minimum outflow from Hells Canyon Dam would be costly to customers based on current power prices, he said.

Largely due to downstream uses, the company operates at 6,500 cfs — 1,500 above the current minimum — and “we try to maintain that 8,500 as much as we can,” Bowlin said. “Some years we are able to do that, but we have to have the flexibility to operate our system.”

Jet boating and whitewater rafting in the canyon have a major economic impact, said Aaron Lieberman, Idaho Outfitters & Guides Association executive director. When flows drop below 6,500 cfs, certain boats cannot get upstream and the canyon’s “big water” allure fades.

“And things get more complicated and way less fun when flows drop below 8,500,” he said.

For nearly 20 years, outfitters had an informal agreement with Idaho Power to keep outflows at 8,500 cfs from Memorial Day weekend to early October, Lieberman said.

“In the last three to five years, we started to see that more or less go away even in normal or high water years,” he said. The reason could be that as renewable energy comprises more of the portfolio, the profitability equation changes.

The irrigation-focused Idaho Water Users Association’s main concern with HJM 9 is that it was drafted without input from the Hells Canyon complex owner, executive director and general counsel Paul Arrington said.

The memorial was introduced Feb. 26 but had not had a hearing as of March 8.