WALLA WALLA, Wash. – Warming temperatures followed by a significant storm off the Pacific Ocean on Saturday and Sunday are forecasted by the National Weather Service to pass through Idaho and parts of Eastern Washington and Oregon. River flows are anticipated to reach near-, at- or above-flood stage on several river within the Snake River Basin, according to the National Weather Service River Forecast Center which can be found online at http://www.nwrfc.noaa.gov/rfc/.
Starting next week, another larger system is forecasted to bring several more inches of rain with the potential to cause major flooding on a number of rivers within the Snake River Basin. Throughout National Weather Service’s forecasted period, the freezing elevation is expected to be in the 8,000 to 10,000 foot elevation – resulting in significant snowmelt.
Early forecasts indicate that this will be one of the top five years on record. Snake River Basin water volumes are forecasted to be similar to 1997.
In anticipation of increased snowmelt and inflows, the Walla Walla District continues to coordinate with state and local emergency management agencies. The Corps has prepositioned more than 50,000 sand bags in Payette and Gem Counties, as well as the City of Horseshoe Bend. Idaho Bureau of Homeland Security, county and city emergency management agencies are taking additional precautions.
Corps water management officials are coordinating with other federal and non-federal dam managers to make adjustments in river system operations that will best accommodate the increased inflows:
The Boise River flows are being maintained below flood stage by Lucky Peak Dam to make flood control space in the Boise System. At the moment the Boise System is 65 percent full. Discharge from the dam is currently 9,700 cubic feet per second (cfs) with flows at the Glenwood Bridge gauge at about 6,800 cfs.
Rainfall over the past weekend left only 9,000 acre-feet of flood control space in Ririe Dam’s reservoir on Willow Creek. Water managers have begun increasing discharges incrementally to avoid causing localized flooding. Discharges were recently increased from 1,600 cfs to 1,900 cfs in an effort to draft additional space in the reservoir ahead of storms forecasted to occur next week.
In the upper-Snake River system, the current flood control space objective is to make 1,600,000 acre-feet of space, however inflows will likely be too high as most of the snowpack telemetry gages are showing evidence of active snowmelt. Jackson Dam is releasing 7,000 cfs and currently has 381,000 acre-feet of space and is drafting about 10,000 acre-feet per day. Palisades Dam is releasing 18,000 cfs and currently has 1,060,000 acre-feet of space and is slowly filling.
The Portneuf River at Pocatello is forecasted to reach 10.43 feet (moderate flood) early next week, followed by higher levels later in the week. At 10 feet, moderate to significant flooding is expected along the river in and near Pocatello, with water flowing over portions of bike paths and trails in Sacajawea Park and North City Park.
The Henrys Fork near Rexburg is forecasted to reach a stage of 10.24 feet early next week, also a moderate flood stage. It is also forecasted to continue to rise later next week. Minor flooding of farmland near the river is possible. Beaver Dick Park is expected to see water with some picnic shelters becoming inaccessible. Areas with low-elevation along Plano Road may have water across the road. The Henry's Fork peaked in June last year at 11.3 feet.
The Snake River near Shelley is forecasted to peak above flood stage at 12.12 feet early next week, followed by additional increases later in the week. The river will see moderate flooding with impacts mostly in lower-elevation areas.
The Snake River at Blackfoot is forecasted to peak above flood stage at 10.92 feet next week. This is just below moderate flood stage, but is forecasted to continue to rise late next week. Minor flooding will occur near Rose. Minor flooding of lowland areas is possible along the river downstream from Blackfoot.
The Imnaha River is forecasted to peak late Sunday or early Monday at 6.11 feet (moderate flood stage). Impacts at this stage include minor lowland flooding.
The Grande Ronde River is forecasted to peak at 9.52 feet over the weekend. This is just below flood stage (10 feet). Impacts could include minor lowland field flooding.
The Bruneau River at Hot Springs peaked on Monday and is forecasted to peak again late next week.
The Teton River is forecasted to reach flood stage late next week. Impacts could include lowland flooding along the river near Sugar City and Rexburg.
Lt. Col. David Caldwell, Walla Walla District commander, said the organization will continue to carefully watch the evolving situation and respond, when requested, with whatever assistance is authorized, appropriate and available.
The Corps is authorized to work with states, counties and other public entities to provide necessary resources and information. The Corps does not have authority to provide disaster assistance directly to individuals.
The first responsibility for protecting homes and property from flood damage rests with the individual. Local governments and agencies, such as flood control districts, may share in this responsibility, and together form a community's first line of defense in preventing flood damages.
Occasionally, however, local resources are not able to control or contain a flood emergency situation. The Corps’ flood disaster assistance program is intended to supplement and assist local governments, institutions and special-purpose districts when more help is needed.
Walla Walla District emergency management officials are prepared to assist states and municipalities with flood-management support, if requested, said Jeff Stidham, Walla Walla District emergency management specialist. That assistance could include technical expertise, supplies and materials, equipment or contracts for emergency flood-fighting work.
“We're watching rivers and streams throughout the Walla Walla District and staying in touch with local emergency officials so, if requested to, we can plan, prepare or act,” said Stidham. “Our top priority is the public’s safety, so we’re encouraging folks in low-lying parts of flood-prone areas stayed tuned to information and advisories provided by the National Weather Service or their local emergency-service agencies and be ready to take action according to local flood response plans.”
State and local agencies needing disaster assistance from the Corps should contact the Walla Walla District Emergency Management Office at (509) 527-7146, or (509) 380-4538.
Individuals are encouraged to contact local emergency management agencies to ensure they understand how to receive updates and information.
For more information about Emergency Management Assistance, check out the District’s Web site at www.nww.usace.army.mil/html/offices/op/em/flodasst.htm or call (509) 527-7145.
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