Brownlee water levels a balancing act

April 20, 2006 12:00 am
The Snake River floods the lawn at the Kirby Creek Lodge when Hells Canyon Dam's outflow exceeds 80,000 cfs; over 90,000 cfs can flood the lodge itself. (Submitted photograph).
The Snake River floods the lawn at the Kirby Creek Lodge when Hells Canyon Dam's outflow exceeds 80,000 cfs; over 90,000 cfs can flood the lodge itself. (Submitted photograph).

By JAYSON JACOBY

Of the Baker City Herald

Idaho Power Company could have kept Brownlee Reservoir full through the end of March, but company officials chose instead to lower the reservoir by more than 40 feet to reduce the risk of flooding in April below Oxbow and Hells Canyon dams.

No matter which of those two options officials picked, however, Idaho Power must lower Brownlee at least 52 feet by April 30 to comply with a federal mandate for flood control, said Roger Fuhrman, director of water management for Idaho Power.

The company, based in Boise, owns and operates Brownlee, Oxbow and Hells Canyon dams on the Snake River east of Baker City.

To put this spring's situation another way, although the U.S. Army Corps of Engineers has ordered Idaho Power to draw down Brownlee 52 feet by the end of April, the company had two options to reach that target: Start the drawdown in late winter and lower the water slowly, which Idaho Power has done; or keep the reservoir full through March, and then empty it rapidly during April.

"It's a balancing act," Fuhrman said Wednesday. "You're always making choices."

The company's decision to draw down Brownlee gradually, though it might have prevented downstream flooding earlier this month, has stranded some boat ramps above the water for several weeks since late winter.

And that in turn has driven customers away from businesses in towns such as Richland and Huntington, where many merchants depend on boaters' and anglers' dollars.

"Just since mid-March I've had 60 cancellations," said Theron Hampton, who owns The Hitching Post motel in Richland.

Fuhrman, who is acquainted with Hampton, said he sympathizes with businesspeople who suffer when Brownlee's boat ramps go dry.

"I know several people whose livelihoods depend on the reservoir," Fuhrman said. "We know this is disruptive."

Huntington Mayor Donna Rush said an official from the Corps of Engineers told her that Idaho Power could have left Brownlee full through March 30, and kept the reservoir within 18 feet of full as late as April 15. At 18 feet below full pool, most of Brownlee's boat ramps are accessible.

Those figures are accurate, said both Fuhrman and Joe Saxon, who works at the Corps of Engineers office in Walla Walla, Wash.

But had Idaho Power followed that schedule at Brownlee, the Snake River might have flooded the company's Copperfield Park below Oxbow Dam, and the Kirby Creek Lodge below Hells Canyon Dam earlier this month, Fuhrman said.

Here's why:

When Brownlee is full or nearly full, the reservoir can't hold much excess water, and Idaho Power must allow most of the water that flows into the reservoir to pass through Brownlee Dam into Oxbow and Hells Canyon reservoirs, and eventually through Hells Canyon Dam, the farthest downstream of the trio.

Fuhrman said company officials decided not to keep Brownlee full through March because they feared that when the above-average mountain snowpack began to melt, a glut of water would flow into Brownlee.

By lowering Brownlee during March, to 42 feet below full by the end of that month, Idaho Power officials hoped to make room in the reservoir to hold enough water to stave off flooding.

That's basically what happened in early April.

A gauging station on the Snake River at Weiser, Idaho, several miles upstream from Brownlee, showed that the river's flow increased from 38,670 cubic feet per second (cfs) on April 2 to 59,246 cfs on April 6.

Had Brownlee been full at that time, according to Idaho Power's projections the company would have had to dump water through Hells Canyon Dam at a rate of slightly more than 90,000 cfs — 10,000 cfs more than the level the company strives not to exceed.

Fuhrman said that at 90,000 cfs, Kirby Creek Lodge, which is run by Snake River Adventures in Lewiston, Idaho, might have been inundated.

Instead of being full, Brownlee was about 45 feet below full when the snowmelt-swollen Snake River began to rise rapidly during the first week of April.

To put into perspective the volume of water flowing into Brownlee at that time, Fuhrman points out that even though Idaho Power dumped water from Brownlee at a faster rate — the flow out of Hells Canyon Dam reached 70,000 cfs that first week of April — Brownlee's level actually rose for a few days because water was pouring into the reservoir faster than it was pouring out of the dam's spillways.

Idaho Power boosted the outflow from Hells Canyon Dam to about 80,000 cfs last weekend, and the flow has stayed near that level since.

Mike Luther, who works at Kirby Creek Lodge, wrote in an e-mail Wednesday that he hopes "the hole in Brownlee is big enough" — in other words, that there's enough room in the reservoir to hold the spring runoff, much of which will arrive during the next month or so.

"Yes, the water is high," Luther wrote in his e-mail. "It is on (the) edge of (the) lawn now. It can go to about 94,000 (cfs) before it's in the lodge."

That last happened on New Year's Day 1997, he wrote, when an unusually mild rainstorm melted deep snow and caused widespread flooding in Northeastern Oregon.

Protecting Kirby Creek Lodge was not, however, the only reason Idaho Power officials decided to draw down Brownlee during March, Fuhrman said.

Had Brownlee been full when the Snake River crested in early April, flooding also could have happened at Copperfield Park and at Pittsburg Landing, a site below Hells Canyon Dam where the Nez Perce Tribe raises juvenile chinook salmon in ponds near the Snake River.

Fuhrman said Idaho Power also strives to avoid lowering Brownlee rapidly, which the company would have had to do during April had it kept the reservoir near full throughout March.

Quick drawdowns can contribute to landslides on the reservoir's steep shorelines, Fuhrman said.

Hampton, the Richland businessman, said that despite his disappointment about Brownlee's low level this spring, he understands why Idaho Power officials picked the gradual drawdown rather than the dramatic one.

In fact, Hampton said he prefers gradual drawdowns because rapid fluctuations in in Brownlee's level tends to foul up fishing.

But Hampton said he wishes Idaho Power had held Brownlee up by just 10 feet or so during the past several weeks.

That, at least, would have allowed boaters to launch at Hewitt Park, he said.

"Barely launchable's all we need," Hampton said. "It sure would have helped."