The U.S. Army Corps of Engineers recently announced changes in its winter operations at Albeni Falls Dam, which is just upstream from Newport. The operational changes will allow the Corps to store water in Lake Pend Oreille in the winter and then release it when it is needed for its dams on the Columbia River during cold weather events or wintertime power emergencies. Previously, the annual minimum winter lake level for Lake Pend Oreille was either 2,051 feet or 2,055 feet above sea level. Under the new operation parameters, once kokanee spawning is completed (usually mid to late December), the Corps will be able to fluctuate the lake level up to 5 feet, at a rate of no more than 6 inches per day.
The new winter operation regime will affect Pend Oreille PUD’s Box Canyon Dam, which is located 55 river miles downstream from Albeni Falls Dam on the Pend Oreille River, as well as property owners along the river. During periods of extreme cold, increased water discharged from Albeni Falls Dam has the potential to break-up any ice that may have formed on the river, which could result in large amounts of ice moving down the river. For homeowners along the Pend Oreille River, the free flowing ice has the potential to cause damage to docks and property. At Box Canyon Dam, increased ice will cause ice jams that could result in reduced power generation and increased operating expenses.
When river flows exceed the powerhouse capacity at Box Canyon Dam because of increased discharges out of Albeni Falls Dam, Pend Oreille PUD will be forced to spill water, resulting in potential loss of revenue, increased safety hazards and operational concerns. “Having to spill water during cold temeratures can cause extremely hazardous conditions and increased operational expense”, said Terry Borden the manager at Box Canyon Dam. Ice buildup at the spillway occurs when spilling water at temperatures below freezing. The spray mist from water spilling over the gates forms ice on the dam structures, gates and cranes. This buildup of ice requires deicing on a regular basis to insure that the crane and spillway gates are functional when needed.
“Although the Corps plans to mitigate potential ice damage by monitoring weather and river conditions before and after water releases, it’s important for our customers to be aware of the potential effects”, Borden added.
