Wednesday, June 9, 2010

Persistent rains raise flooding concerns

River flows spike; residents warned to avoid fast-moving water

Express Staff Writer

Photo by Jeff Ledford Heavy rains contributed to high flows in the Big Wood River that flooded the lawn of this riverside home at the base of Della Mountain on Sunday.

Heavy rains over the weekend caused a quick spike in flows of the Big Wood River and its tributaries.

The rains, combined with a warming trend that's finally begun to melt high-elevation snowpacks after an unusually cool April and May, quickly turned the river into a mud-colored soup. The rapid increase in river flows is surprising given the poor winter snowpack and predictions by water officials that the state would likely experience low runoff levels this spring.

As of Tuesday morning, the Big Wood was flowing at a sizeable 4.75 feet, or 2,540 cubic feet per second (cfs), measured by the river gauge at the Bullion Street Bridge on the west end of Hailey. Official flood stage on the Big Wood is 6 feet.

The current flows along the Big Wood are nowhere near those recorded during the record-setting flood year of 2006. At its peak on May 21, 2006, the river reached a height of 7.92 feet and was flowing at a whopping 7,800 cfs. Officials at the time stated that the 2006 flows were the highest ever recorded along the Big Wood.

While the river hasn't achieved official flood stage, the rising flows have caught the attention of some local homeowners along the river. On the south end of Hailey in places like the Della View neighborhood, the high flows have begun to lap at some riverside lawns.

On Tuesday, Blaine County Disaster Services Coordinator Chuck Turner said one of his greatest fears is that local residents may think the river isn't dangerous because it's not at official flood stage. Turner said the current flows are deceiving. He said parents should be careful to keep their children—who have just now entered their summer break and may looking for things to do—from playing around the river.

"It's very deceptive looking," he said. "Don't be playing in it or around it. There's no reason to be there."

The heavy rains and rising flows led the National Weather Service to release several flash flood warnings over the weekend and early this week. One advisory released on Friday briefly mentioned that a rockslide had occurred near Galena Summit.

The flash flood warning stated that campers and other recreationists need to be extra cautious along fast-flowing streams and rivers as the rains continue.

"It is important to know where you are relative to streams, rivers or creeks, which can become killers in heavy rains," the advisory stated. "Campers and hikers should avoid streams or creeks."

So far, the June rain totals in the Wood River Valley have accumulated at a fast pace. However, a lot must happen before the rains come anywhere near the totals recorded last June, said Mike Huston, a forecaster with the National Weather Service in Pocatello.

According to the official rain gauge at the Sawtooth National Forest's Ketchum Ranger Station, the valley has received 1.03 inches of rain so far this month. Normal for June in Ketchum is 1.51 inches.

But that's nowhere near last June's rain totals, when a succession of storms led to a record 5.29 inches of rain in Ketchum.

"We've got a ways to go before we get anything like last year," Huston said.

He said that while rains are expected to return to the valley today and last through next week, longer-term predictions are calling for an eventual drying trend to arrive in Idaho.

Harder hit by the heavy rains than Blaine County and the rest of south-central Idaho have been sections of western Idaho. There, Valley County officials have been forced to close some roads in and around McCall.

According to online reports from Northwest Cable News, county officials have shut down Warren Wagon Road north of Dead Horse Creek because of the heavy rains. The road leads from McCall into the remote hamlet of Warren. A bridge along the road became impassable and was threatened after it became clogged with woody debris, pushing the rare high flows over its top.

Also closed for the time being in the McCall area are portions of East Side Drive and Lick Creek Road.

On the North Fork of the Payette River, a popular destination for expert kayakers that flows out of Cascade Reservoir, the river was running at a thumping 6,500 cfs on Tuesday. Rainfall-swollen tributary streams are only adding to the remarkable flows on the raging North Fork.

The rains caused significant flooding last Friday and over the weekend in Valley and Beaver creeks over Galena Summit in the Sawtooth Valley.

Jason Kauffman:

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