Hydroelectric production levels in the Pacific Northwest (PNW) dropped significantly in August from both year-ago levels and from the previous month as well below-normal levels of precipitation during the month appeared to impact the availability hydropower supplies in the region.

According to data from the US Army Corps of Engineers, total net electricity generation at 23 hydroelectric plants across the PNW dropped in August to 4.51 million MWh or nearly 8% below the year ago level and nearly 15% below the ten-year average level. Hydroelectric generation in August was also reported to have dropped by more than 15% versus July levels. Although strong production earlier in the year pushed output above year ago levels, the continuing drought has year-to-date hydropower production levels 6% lower versus the ten-year average. In the upper Columbia River Basin, both Grand Coulee and Chief Joseph Dams saw production levels drop by 13% from July levels and by 10.8% and 14.1% respectively versus August 2015 levels. The Bonneville Dam and The Dalles Dam located in the Lower Columbia River Basin also faltered versus the ten-year average during the month with Bonneville and The Dalles down 32% and nearly 16% respectively.

Although hydroelectric power production normally reaches a low during the months of September and October, the months that mark the end and beginning of the water year, the ongoing drought appears to continue to impact output and add uncertainty to supply. Initial weather outlooks for the winter season bring hope of higher than normal snowfall which could bring much needed snowpack to the region, but the impact of actual weather will not be known for many months.

Source: SNL, US Army Corps of Engineers