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Brownlee low, will get lower
By JAYSON JACOBY
This year hasn’t had nearly as soggy a start as 2011 did, but the situation at Brownlee Reservoir, Baker County’s most popular boating and fishing spot, is pretty much the same.
Which is to say, dry.
Brownlee, the 53-mile-long reservoir on Baker County’s eastern flank that forms the border between Oregon and Idaho, is about 50 feet below full today.
And the reservoir is dropping, leaving boat ramps on the Oregon shore, most of which are already unusable, even farther above the water line.
A brief explanation is in order for what might seem counterintuitive: A reservoir that shrinks not only during dry years, but also during damp ones such as 2011.
Put simply, it’s all about flood control.
Brownlee is a key cog in the flood control system for the lower Snake and Columbia rivers.
Although Idaho Power Company owns and operates Brownlee Dam, during late winter and through at least part of the spring a federal agency, the U.S. Army Corps of Engineers, basically tells Idaho Power how much water to dump through Brownlee’s spillways.
The basic idea, said Kresta Davis-Butts, a hydrologist at Idaho Power’s headquarters in Boise, is that the Corps of Engineers requires the company to maintain a certain amount of space in Brownlee to temporarily store runoff from rivers in Idaho and Oregon that empty into the reservoir.
Holding some of that water in Brownlee reduces the risk of flooding downstream along both the Snake and Columbia.
The counterintuitive part perhaps begins to seem less so — the wetter it is, the more water must be taken out of Brownlee to make room for runoff.
That relationship certainly explains why Brownlee was well below full throughout the chilly and wet spring of 2011.
This year, though, hasn’t been especially wet or cold, at least in Eastern Oregon.
Rainfall for the first three months of the year in Baker City was barely half as much as for the same period in 2011 — 1.66 inches compared with 3.49 inches.
But rainfall is only one variable in a more complex equation, Davis-Butts said.
Other variables include:
• Mountain snowpack in a region stretching from Canada, where the Columbia begins, to the headwaters of the Snake River in Wyoming
• The amount of water stored in smaller reservoirs upstream from Brownlee.
In both cases, she said, conditions are quite similar to last year.
A series of storms during March boosted snowpacks in Eastern Oregon and Idaho to near, and in a few cases above, average.
The most significant statistic, though, is the level of those upstream reservoirs.
Reservoirs in the Boise and Payette basin, for instance, are holding about 25 percent more water than they did a year ago, the lingering legacy of last year’s bountiful snowpack and heavy spring rains.
Even accounting for this year’s slightly shallower overall snowpack, and the scarcity of rain compared with 2011, the extra water in the reservoirs means about the same volume of water will flow through those dams and thence into Brownlee.
The result, Davis-Butts said, is the Corps of Engineers has ordered Idaho Power to drop Brownlee to 52 feet below full by April 15, and to 63 feet below full by April 30.
Those numbers are nearly identical to those from 2011, when Brownlee, at the end of April, was 62 feet below capacity.
Idaho Power officials have had only preliminary talks with the Corps of Engineers about when the company will be able to start refilling Brownlee, Davis-Butts said.
The company’s goal in that respect is the same as it has been for many years: To have the reservoir as close to full as possible by Memorial Day weekend.
Achieving that goal is not only crucial to the bottom lines for businesses in Huntington, Richland, Halfway and other towns that depend on Brownlee anglers and boaters, it also helps Idaho Power produce more electricity.
Brownlee is the company’s biggest producer of hydropower.
Last spring the Corps of Engineers allowed Idaho Power to start refilling Brownlee around May 10.
The reservoir went from 60 feet below full on May 9 to 31 feet below full two weeks later.
Brownlee didn’t reach full pool until the last week of June.
Idaho Power might get to start the refilling process earlier this spring, Davis-Butts said.