(AP) -- Wind farms and fossil-fuel power plants in the Pacific Northwest were all but shut down for five hours early Wednesday as the Columbia River basin's hydroelectric generators ran at full capacity and river managers dealt with one of the largest volumes of spring runoff in years.

The Bonneville Power Administration said last week such a shutdown was likely and may be repeated overnight Thursday. Wind farm operators have objected.

During the shutdown, from midnight to 5 a.m., almost all Northwest power came from dams.

The Bonneville Power Administration says and coal and natural-gas plants reduced output to the minimum needed to protect their equipment and the grid. Customers were not affected.

The agency says the water volume is so great that fish trying to get by the dams are in jeopardy from turbulence and nitrogen in the water.