Portland, Ore. – River levels between John Day and McNary dams could be higher during the next three months, the U.S. Army Corps of Engineers announced today.
From October through December, Lake Umatilla, the section of the Columbia River above John Day Dam, will be operated in a broader and higher range. That means river users could see river levels 2.5 feet higher than in the spring and summer.
This operation is pursuant to requirements spelled out in a biological opinion to support juvenile anadromous fish migration, maintain minimum water levels for irrigation withdrawals, and to accommodate Tribal treaty fishing operations.
The expanded operating range during October will be from 262.5 to 266.5 feet. However, the Corps intends to operate the reservoir in a narrower 1.5 foot range if Tribal treaty fishing extends into October.
In addition to the higher levels, users may also see more variability than in recent months. Once irrigation season is deemed over, the operating range for most of November and December will be from 262.0 to 266.5 feet. This wider operating range provides additional storage to reduce downstream impacts from winter storm events and helps support chum salmon spawning requirements below Bonneville Dam.
The Corps requests feedback at any time if higher pool levels cause or are expected to cause problems for affected parties. For flood risk management purposes, in the event of potential flooding in the Portland metro area, the full operating range from 257 to 268 feet may be utilized.