BAKER CITY — This summer Idaho Power is approaching crucial milestones towards the federal relicensing of its Hells Canyon dams.

The Hells Canyon dam complex has been subject of an intensive environmental survey over the last two decades as the hydroelectric dams accelerate important redesigns to the Brownlee, Oxbow and Hells Canyon dam network.

Entering the final steps into gaining its Federal Energy Regulatory Commission (FERC) license, Idaho Power is putting significant focus on three major conditions:

• Water quality, including pollutants, temperature and oxygenation.

• Ecosystem impacts, such as fish toxicity and reproduction.

• Improving on riverside recreational features.

This summer Idaho Power expects to receive a Supplemental Environmental Impact Survey following two decades of research and surveyor cooperation as the ongoing effects of the dam have been gathered. The survey is a crucial component of the new license, which can guarantee further hydroelectric operations for 20 to 30 years.

The Herald, alongside Hell’s Canyon Journal and Idaho Capital Sun, was recently invited to a two-part tour of the dam complex.

“Our biggest issues are our fish, and our water quality,” said Brett Dumas, Idaho Power’s director of environmental affairs, as reporters toured the top of the Brownlee Reservoir. Below, arm-sized carp idled near the spillway. In a natural setting, carp can be as healthy as any fish, but a dam’s presence affects them in indirect ways, as well as many deep-water species, including the Snake River’s famous sturgeon.

Dumas says in conducting the survey researchers have come to understand a great deal about the food-chain effects of the dams. Mercury especially can cause cascading damage to animals.

“Brownlee is deep. 200 to 300 feet deep,” said Dumas, “Unfortunately, this is a great assist for microorganisms.” Specifically natural and introduced mercury accumulates in riverbed sediment, where bacteria consume it.

“These organisms are attached to it and they’re digesting that sediment. And in their process of doing that they convert mercury to methylmercury.”

When these organisms, called cyanobacteria, are consumed, methylmercury accumulates upward into the food chain, a process known as bio-accumulation. Dumas says that this problem isn’t unique to the Hells Canyon ecosystem, and that the scale of it extends to all reservoirs and lakes.

Dumas said the impact survey covers protected animals such as eagles, and Idaho Power has been keeping an eye on the mercury levels in various species that eat fish.

Improving water quality involves taking an active approach to control the temperatures and low-oxygen conditions that create cyanobacteria. Idaho Power’s relicensing efforts over the next 50 years will be a $1 billion dollar process, one hinging on those improvements.

Action at the inflow

Entering the secure interior of Brownlee Dam, the hum underfoot gives a constant reminder of the natural forces at work. Within, turbines numbered 1 through 5 turn on meter-wide axles of exposed spinning steel. This is where Idaho Power makes its first intervention in water quality.

“It’s carrying a million and a half pounds,” Hells Canyon regional hydroelectric manager Itsy Tanaka points out. “That heat you feel is electricity being made.”

In sync, they produce 675,000 kilowatts, a workload also shared by Oxbow Dam’s 190,000kw and Hells Canyon Dam’s 391,500kw outputs, instantly delivering to roughly 600,000 customers.

The whole complex is maintained by roughly 90 full-time workers, and throughout the tour Tanaka described the many systems and hazards they encounter. In keeping with their commitment to water quality, he illustrated especially the aeration system paired into the turbine’s output.

“We suck air in through the turbine to add oxygen to the river, coming out on the bottom of the turbine,” says Tanaka over the dull roar. “This is what we do to mitigate what the dams do, increase fish habitat and make the water better. This is really awesome engineering.”

The water is also pulled from the bottom of the river, where oxygen is most needed. From the outlet outside, you can see the intense blue churning as it leaves the facility and settles into a calm. The aeration also mechanically cools the water, cooler water stalling the propagation of cyanobacteria.

Idaho Power also mitigates heat buildup by increasing river velocity and depth, adding shade trees to shallow shores and developing flood plains. As summer heats it you can often see floating teal blobs of the bacterial growth on the surface. Industrial wastewater as well adds to its growing potential, accumulating over hundreds of miles.

“You’ve got the Burns River, you’ve got the Powder River, you’ve got Weiser, then Boise, all of those areas are bringing nutrients and sediments in, and Brownlee deals with it all,” said Dumas. “So, boom, there goes your oxygen because you got all this stuff coming in that’s decomposing, and then as that settles now you got a perfect environment for the mercury.”

Many of the pollutants are beyond Idaho Power’s direct control, however, as agricultural and industrial waste along water networks naturally flows their way. Outside the dam’s turbine chambers, agricultural calcium, phosphorus and minerals build up around the doors and accessways, requiring regular removal.

Brett Dumas says that they keep close tabs with the civil works division of the Army Corps of Engineers, which has authority over water quality issues in the nation’s rivers and will be involved in officiating the relicense.

“For years we’ve gone upstream to work with the ag communities to try and reduce the amount of phosphorus and sediments coming into the river and all the tributaries. We have to meet water quality standards so we’re going to have to figure out how to mitigate that,” said Dumas.