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Corps Concerned about Flooding
if Dams Breached

by Mike Lee
Tri-City Herald, April 22, 2000

The Tri-Cities can't lower its rivershore levees as far as planners want because the Army Corps of Engineers is worried about possible flooding if the four lower Snake River dams are breached.

Agency officials Friday said the Corps doesn't really know what would happen to water levels if the dams were removed, so it's better to be careful about taking too much off the nearly 50-year-old levees.

"I was frankly bewildered," said Kris Watkins, executive director at the Tri-Cities Visitor and Convention Bureau, which is pushing for lower levees to make the Columbia River more enticing for tourists and residents. "We had never heard that statement."

An internal Corps' memo obtained by the Herald revealed agency concerns that Tri-City officials said they never had heard from the Corps.

Directions from Washington, D.C., are the agency should use "engineering conservatism" with the levee lowering project because - among other reasons - "there is potential for heightened backwater" behind McNary Dam if the four dams above Pasco are removed.

The memo, dated April 14, did not give details about potential problems.

But Cindy Henriksen, Corps chief of the reservoir control center in Portland, said "prudent management" requires waiting on levee reduction until dam questions are settled.

She did not know why those concerns didn't stop the Tri-City request at the district or division level when it was made last summer.

And her position seemed to contradict that of Lt. Col. William E. Bulen Jr., Walla Walla District commander. After an initial rejection of the Tri-City plan by headquarters, he sent the proposal back to Washington, D.C., in February saying he "strongly believes" the plan makes sense.

Potential levee problems could be caused by the 100 million to 150 million cubic yards held behind the dams that would flow into the McNary pool, also known as Lake Wallula. About half of that mud is expected to flow downstream, but very little is understood about how it will move.

"It's potentially going to change the contour, the structure ... the bottom levels of Lake Wallula, which may put more stress of more water rising on those levees," Henriksen said. But, she added, there is not enough information to say how far the silt load would raise the Columbia.

At the Corps of Engineers Walla Walla District office, spokeswoman Nola Conway said her agency's multi-volume report from last year on the repercussions of breaching the dams did not deal in-depth with rising water levels in the Tri-Cities "because we don't really know what would be the impact."

Corps studies suggest dam breaching would be done in phases, which would give plenty of time to watch where sediments go, Conway said.

"We don't really know if we do need preventative (measures) at this time. What we do know is that it could become an issue," she said. "That's why monitoring (would be) set up so that nothing would happen."

But monitoring alone isn't likely to ease fears in the Tri-Cities. Jim Toomey, executive director at the Port of Pasco, said after attending years of meetings and public hearings about the dams, he couldn't recall hearing agency concerns about the river rising in the Tri-Cities.

"Whoa," he said after hearing about the Corps memo. "That's a total surprise to me."

He said the implications were significant for river shore properties but that with so little detail in the memo, it was impossible to determine the extent of the potential problems.

Pasco City Manager Gary Crutchfield didn't put as much stock in the rising river theory, saying national Corps officials probably were just using whatever tools they had to justify their opposition to levee lowering. The parties have been bickering about the correct height for years.

"It's just one of those 'what ifs' they throw in there to justify their general conclusions," Crutchfield said. "I think it's an afterthought more than a reason."

Whatever the case, the Corps memo poked another hole in the thin bridge of trust between the Corps and the Mid-Columbia, a bridge that was shaken by reports earlier this week that top political appointees at the Corps erased a recommendation not to breach the dams for political purposes. The final dam decision is up to Congress.

"It's really frustrating not to be able to get a straight answer," Watkins said.

Tri-City officials are hoping to lower the levees by at least 7 feet and put all that extra rock into the river as a way of making it less of a channel and more natural. The move is expected to be good for fish habitat and public enjoyment of the river, which in some areas is all but blocked by the towering rock walls.

A portion of the Pasco levee already was lowered in the mid-1990s as part of a demonstration project.

City officials have approval to go down about 6 feet, and they have a report done by HDR Engineering of Pasco that confirms another foot down still leaves plenty of room for flood control. The levees were built after the massive floods of 1948 destroyed large parcels of the Tri-Cities.

Although 12 inches may not seem like a lot, river shore planners say they are critical because every foot off the top means taking 4 feet off the width of the base and bring people that much closer to the river.

The Walla Walla District approved the HDR recommendation for another foot reduction with the caveat that river conditions stay the same as they are now.

The first of two denials from headquarters, issued Dec. 14, came just a few days before the Corps released its massive draft investigation of tearing out the lower Snake dams to improve fish passage.

Mike Lee
Corps Concerned about Flooding if Dams Breached
Tri-City Herald, April 22, 2000

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