Hydroelectric output in the Pacific Northwest climbed versus the prior month in September, a month during which the region's hydroelectric production more often than not reaches its lowest level of the year.
According to the U.S. National Oceanic and Atmospheric Administration, much of the region experienced above-normal precipitation during the month with some areas exceeding 130% of normal.
Data from the U.S. Army Corps of Engineers show that total net generation at 23 hydroelectric plants across the Pacific Northwest was 16.9 % above the year-ago level and 12.4% above the 10-year average as it reached 4.59 million MWh. That figure is up 3.0% from August.
Year-to-date hydropower production through September totaled 64.71 million MWh, up 17.3% versus the year-ago level and up 11.7% from the 10-year average for the period.
In the upper Columbia River Basin, the Grand Coulee Dam, the largest of the region, generated 1.28 million MWh, up 11.9% versus the year-ago month and up 16.6% versus the 10-year average for the period. The Chief Joseph Dam generated 693,055 MWh, up 10.4% versus September 2016 and up 15.0% versus the 10-year average for the month.
September flows in the lower Columbia River Basin were also higher versus the year-ago period. Located on the Washington-Oregon border, the Bonneville Dam produced 352,082 MWh, up 16.3% versus September 2016 and 11.5% higher versus the 10-year average for the month. The Dalles Dam, 50 miles downstream, produced 446,181 MWh, up 22.2% from the year-ago month and up 17.0% from the 10-year average for September.