By the time spring runoff is over, enough water will have crashed through Albeni Falls Dam near Newport to cover Yellowstone Park in 10 feet of water.
Boosted by heavy rains over the past two weeks, rivers in the region are roaring. Some, including the Spokane River, are already above flood stage.
Rivers with high mountain drainages, like the Pend Oreille, haven’t seen their heaviest flows yet. River managers say they probably will flood, too.
The Pend Oreille River is expected to double in volume by June. Flooding is predicted by late May in low-lying areas northwest of Newport.
“It’s running pretty good,” said Albeni Falls dam manager Bob Schloss. He has the spill gates wide open to prevent water from backing up in Lake Pend Oreille.
“We are trying to make sure people are prepared,” said Patricia Graesser, spokeswoman for the U.S. Army Corps of Engineers, which oversees flood control.
Last week, Army Corps flood teams visited Sandpoint and St. Maries to help local officials plan. Levees are being raised along the St. Joe River. More than 47,000 sandbags were delivered to Benewah and Kootenai counties.
“We haven’t seen this much water up in the hills in a long time,” Graesser said.
Coming out of the winter, snowpacks piled up to 150 percent of normal. The National Weather Service is predicting the runoff on the Columbia River at The Dalles, Ore., will be 134 percent of normal. The last time so much water drained out of the Columbia Basin was in 1974.
Because flood-control dams have been built throughout the basin, water managers say they can slow the high flows on main stems like the Columbia and Snake to prevent serious flooding. Only the low-lying Portland-Vancouver harbor on the Columbia should be affected.
A wet spring is aggravating the situation. Nearly 2-1/2 inches of rain fell in Spokane in late April, causing the Spokane River and its tributaries to go above flood stage.
Last Monday, more than twice as much water was flowing into Lake Coeur d’Alene as was flowing out through the dam at Post Falls, which has been left wide open.
Cooler weather at the end of the week slowed the snow melt and allowed the flood threat to subside for now.
Lake Coeur d’Alene came close to flooding, and the high lake level caused the Spokane River to reach flood stage. Because the Spokane River has steep banks, flood problems are relatively minor.
But Bloomsday crowds this weekend will feel the thunder of the falls in flood.
The river is expected to crest in the next few days at or above the extreme flows reached on Feb. 12, 1996, when the river was measured at 36,000 cubic feet per second at the gauging station in Peaceful Valley west of downtown.
On Friday, the flow was reported at 34,000 cfs. The river is expected to continue flowing at or near flood conditions for at least two more weeks.
Spillways at most major dams will be dropping long white curtains of water.
Reservoirs at Grand Coulee and other flood-control dams have been dropped drastically to absorb the runoff.
The water level behind Grand Coulee was being lowered this week to 82 feet below full pool.
The reservoir behind Dworshak Dam on the North Fork of the Clearwater River east of Lewiston was 145 feet below full pool.
“We’ve just started to melt out,” said Brian Avery, a hydrologist for the National Weather Service in Spokane.
Emergency management officials are taking the threat seriously.
In Montana, more than a quarter million sandbags are being stockpiled.
Counties in Eastern Washington and North Idaho are making plans to respond to the flooding.
The Pend Oreille River, which drains 24,400 square miles in North Idaho and western Montana, should release about 21 million to 23 million acre feet of water in the next several months. That’s enough to fill and drain Lake Pend Oreille 23 times.
To reduce the threat of flooding on Lake Pend Oreille and the river, dam managers have dropped the level of Hungry Horse Reservoir in western Montana to catch about 2 million acre feet of runoff. The reservoir was 120 feet below full pool earlier this week.
The Pend Oreille on Friday was flowing at 69,000 cubic feet per second. That’s more than a half-million gallons of water every second.
Forecasters say the river flow will nearly double to 130,000 cfs by June.
When those flows arrive, low-lying areas near Cusick and the river bend downstream will flood, Avery said.
The level of Pend Oreille Lake was at 2,057 feet above sea level earlier this week, just 6-1/2 feet below flood stage. Forecasters say the lake may reach or slightly surpass flood level.
Elsewhere, the Okanogan River could overflow its banks and cause damage from Tonasket downstream.
Avery said he also expects flooding on the Entiat, Sanpoil, Wenatchee and Methow rivers of north-central Washington.
Shippers on the Columbia and Snake rivers are having trouble negotiating the heavy currents below the dams, particularly at John Day Dam, where spillway water has created dangerous cross currents near the shipping locks.
Clare Perry, a spokeswoman for the Army Corps in Portland, said the agency is working on ways to spill water so that it won’t cause swirling currents.
The nerve center for the region’s flood control is the Reservoir Control Center in Portland, which is operated by the Army Corps. Workers there hold daily briefings on the latest weather, snowpack depths and runoff patterns, and give dam operators orders for managing the high flows.
In the past week, the corps ordered dams on the Snake and Columbia rivers to begin spilling water to make some room for the crest of the flows in June.
“We are not seeing the main runoff yet,” said Albeni manager Schloss.
, DataTimes ILLUSTRATION: 2 Color Photos; Graphic: Flood control