Pacific Northwest hydropower production remained below historical averages in July, when observed precipitation over much of the region was less than half of normal.
According to the U.S. National Oceanic and Atmospheric Administration, precipitation was less than 50% of normal for about three-fourths of the Columbia River Basin in July, and above normal for the northern section of the region. The weather was cooler than normal for the northern and western portions of the region, near normal for the midsection and warmer than normal for the southern part.
Data from the U.S. Army Corps of Engineers show that total net generation at 23 hydroelectric plants across the Pacific Northwest in July was 19.0% below the year-ago level and 28.1% lower than the 10-year average as it reached 4.83 million MWh. That figure is down 24.0% from June.
Year-to-date hydropower production through July totaled 41.19 million MWh, down 24.0% versus the year-ago level and down 17.6% from the 10-year average for the period.
In the upper Columbia River Basin, the Grand Coulee Dam, the largest of the region, generated 1.70 million MWh, down 21.5% versus the year-ago month and down 29.6% versus the 10-year average for the period. The Chief Joseph Dam generated 899,588 MWh, down 21.1% versus July 2018 and down 22.0% versus the 10-year average for the month.
July flows in the lower Columbia River Basin were also lower than the year-ago period. Located on the Washington-Oregon border, the Bonneville Dam produced 122,253 MWh, down 40.3% versus July 2018 and 56.3% lower than the 10-year average for the month. The Dalles Dam, 50 miles downstream, produced 327,074 MWh, down 21.6% from the year-ago month and down 33.3% from the 10-year average for July.