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Rain improves water outlook

by Brian Walker
| June 10, 2010 9:00 PM

POST FALLS - Recent rain and cool weather have at least temporarily staved off expected near-drought summer conditions, according to a recent report by the Natural Resources Conservation Service.

"This winter's lack of snow was predicted to cause water supply deficits across parts of Idaho," according to the report. "However, the cool, wet spring helped to overcome most shortfalls."

May brought 134 percent of average precipitation to North Idaho. Cool temperatures prevented north-facing slopes from losing much snow and delayed streamflow peaks.

"The El Nino weather pattern snapped the last week of March and storms since then have brought average or better precipitation," said Ron Abramovich, NRCS water supply specialist. "These weather changes resulted in an incredible turnaround. We now expect adequate water supplies for most of Idaho's numerous users."

However, area snowpack is still ranging from 56 to 77 percent below normal.

The lowest streamflow forecasts for the region call for 55 to 65 percent of average for the North Fork of the Coeur d'Alene, St. Joe and Spokane rivers through September. The best forecasts are from 75 to 85 percent of average for the Kootenai, Clark Fork, Pend Oreille and Priest rivers to the north through summer.

"The melt water isn't there to feed the streams yet because the cool weather is limiting snowmelt," Abramovich said.

Patrick Maher, senior hydro operations engineer for Avista Utilities, which operates the Post Falls Dam on the Spokane River, said the recent rain will help hydro generation later in June as the groundwater and high-level snow conditions have improved.

He said the situation has helped the company's Montana operations more than on the Spokane River.

"The higher elevations in Montana allows the mountains to capture more of the moisture in the form of snow," Maher said. "On the Spokane River, because we have limited generation capacity, if we get too much rain too fast, the water is simply spilled over the tops of the dams. This has been the case with the recent rain storms."

Maher said Avista has had all hydro generation on the Spokane River maxed out for the past two months. Additional water is spilled over the dam through spill gates.

"If normal or above normal rains continue into late June and July, Avista can take advantage of that water if the river flows stay near the capacity of the generation turbines for a longer period of time," he said.

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