For the week of March 24, 1999  thru March 30, 1999  

Riverside residents brace for high water

Early, gradual melt-off may ease threat

Express Staff Writer

m24water.jpg (19542 bytes)Avalanche specialist Janet Kellam shows how deep the snow was at its peak at the Ketchum Ranger District office on Sun Valley Road. (Express photo by Willy Cook)

This season’s higher-than-average snowpack poses yet another threat of flooding to residents living along the waterways of Blaine County.

Although not as foreboding as the record snowpack of the spring of 1997 that flooded parts of Blaine County and caused widespread damage around the Northwest, it deserves respect, officials said. The spring tallied in at 160 percent of the 30-year average for water content in the snowpack.

According to Gale Roberts at the Hailey Soil Conservation District office, the water content in the snowpack in the Big Wood River drainage is currently 120 percent of the 30-year average, down only slightly from numbers posted earlier this winter. The Stanley Basin is 127 percent of the average.

The fact that the current numbers are down only slightly from those recorded earlier in the winter means that, despite recent warm temperatures, snow at higher elevations is retaining moisture.

"Nothing at or above 6,400 feet has started to melt off yet," Roberts said.

The snowpack below 6,000 feet has begun to melt, he said, but low-elevation melts do not significantly contribute to runoff or river swelling. Local streams and rivers have probably risen slightly, he said.

If temperatures continue to rise gradually, as they have over the past two weeks, "that would be good," Roberts said.

"The more water we get melted off before June 1, the better," he said.

Traditionally, the Big Wood River peaks during the first week in June. If snow gradually melts off before the traditional peak, this spring’s high water mark will likely be lower.

Conversely, it is more beneficial for Bellevue Triangle ranchers and farmers if the water does not melt off early, Roberts said. The triangle is an area of Blaine County bordered by State Highway 75, U.S. Route 20 and Gannett Road.

"Early spring runoff can cause late season dry periods because there is no storage there," Roberts said.

Ranchers and farmers below Magic Reservoir, in Fish Creek drainage north of Carey and in the Little Wood Drainage do not depend as heavily on the timeliness of runoff. The dams catch the water whenever it melts and fills the streams, Roberts said.

But Roberts pointed out that the rivers haven’t really started moving at all yet and, traditionally, about three more weeks of precipitation remaining this spring.

Elsewhere in the Northwest, the snowpack’s water content is much higher than normal.

Washington’s Olympic Peninsula is currently at more than 200 percent of the 30-year average for water content in its snowpack. Areas throughout Oregon, Idaho and Washington currently vary between 120 and 200 percent of the average, with the highest concentrations of moisture in Washington’s Cascades.

In the spring of 1997, when the water content in the snowpack topped 160 percent of the 30-year average in the Wood River Valley, the melt-off began rapidly in mid-May and crested during the weekend of May 16. Then-governor Phil Batt was forced to declared a state of emergency for all of Idaho’s 44 counties as floods and mudslides inundated the state.

Locally, the Big Wood River topped off at a depth of 6.4 feet, a half foot above flood stage. Sheet flooding and water damage to some riverside homes resulted, but most residents were prepared for the high water.

Kootenai, Bonner, Shoshone, and Clearwater counties suffered a worse fate. The Idaho National Guard was called in to those areas to help defend residents from the floods and assist with cleanup.

Federal Emergency Management Agency officials recommend that those living in flood-prone areas buy flood insurance early or reevaluate their current flood coverage. Such insurance usually has a waiting period of at least 30 days before it takes effect.

"Our traditional rainy season may be extended this year, and most homeowners’ insurance does not cover flood damage," warned Ray Williams, FEMA deputy regional director for the Northwest in a press release issued last week. "With the (current) snowpack, spring flooding may be more likely, particularly east of the Cascades, and this threat could last through June."


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