FISHERIES -- Snake River dams will begin spilling water to help young salmon and steelhead migrate downstream to the ocean. The spills start Sunday at Snake River dams and Monday at four lower Columbia River dams.

The U.S. Army Corps of Engineers announced the details of its 2011 Spring Fish Operations Plan this week.

"We'll be spilling 24 hours a day, seven days a week at all eight mainstem dams during the out-migration season," said Rock Peters, the Corps' fish program manager.

The 2011 spring plan, which closely resembles last year's plan, continues operations for fish passage at the Corps' Columbia and lower Snake River dams. It includes spill and flow, adjustments to river operations and transporting juvenile fish beginning in late April or early May.

Some fish are transported to help mitigate the problem of fish mortality as the young steelhead and salmon negotiate the unnatural conditions created by the dams: slack-water reservoirs, dam turbines and ambushing predators.

In 2010, the Corps transported about 35 percent of the spring migrating fish to below Bonneville Dam.