Idaho Power, the company that operates the three-dam Hells Canyon complex on the Snake River, is warning commercial and recreational jet boaters that flows could get bony in the canyon later this spring and summer.
A snowpack that is well below average across many of the mountains that feed the Snake River means the company may choose to conserve energy in periods of low demand by slashing flows. It also could reduce flows and store water at Brownlee Reservoir when other sources of power such as wind, natural gas and coal are either abundant or cheap and pass the water through electricity-generating turbines during times of high demand or high prices.
The result will be periods where flows, as measured at Hells Canyon Dam, drop below 8,500 cubic feet per second, which is the level commercial jet boat operators say they prefer and the level the U.S. Army Corps of Engineers considers safe for navigation.
“We have seen really record-low precipitation in some areas of the basin,” said Kresta Davis-Butts, leader of Idaho Power’s hydrology group. “The precipitation we saw January through March is the fifth lowest for the state of Idaho and that is a record of 119 years.”
Kresta said the company plans to keep flows at or above 8,500 cfs through May 27 to make sure fall chinook redds are not dewatered and young fish do not become stranded with rising and falling river levels.
“Going below 8,500 is certain at this point,” she said. “Where and how far down that is, we are still uncertain.”
The company’s Federal Energy Regulatory Commission license allows it to drop flows to as low as 5,000 cfs below the dams but the company has an informal policy of keeping flows at or above 6,500 as long as it can do so by passing in flow — water coming from upriver.
Idaho Power sends out an email to commercial operators and some frequent recreational boaters detailing its plans. Mark Yates of Hells Canyon Adventures said there needs to be more give and take between boaters and the company about flows and safe navigation.
“We are not working with them. That is my concern, there is no dialogue anymore,” he said.
Yates said his company, which runs trips starting at and returning to Hells Canyon Dam, books tours about six months in advance. If flows do dip to 6,500 or lower at the wrong time of the day or week, he could have to reschedule those trips, take fewer people or use smaller boats.
The biggest rapids in the upper stretch of the canyon near the dam, become difficult for the large commercial boats — some as long as 40-feet — to run at low flows. Low flows can also make some of the rapids in the lower end of the canyon more difficult for large boats.
But flows are generally more generous below the mouth of the Salmon River. The company is obligated to keep flows on the northern end of the canyon, measured at Lime Point, at or above 13,000 cfs.
Yates said the best bet for adequate flows is hot weather that compels energy customers to run their air conditioners on high and the company to push water through its turbines.
“With a very hot summer they have to pass water.”