Electricity generation stable at Dalles Dam despite high annual water flow

While water flow along the Pacific Northwest’s Columbia River has reached higher than normal levels this year, electricity generation at Dalles Dam has remained largely stable, since much of the excess water has spilled and thus diverted past the dam without generating power.

Unlike some of its counterparts, which act as storage along substantial reservoirs, the Dalles Dam is a run-of-river hydroelectric facility, meaning it comes with only limited storage capacity and continues to pass the rest of the water flowing through it downstream. Despite this, it is one of the country’s 10 largest hydroelectric power plants.

Lower than average temperatures coupled with above-normal precipitation last winter, followed by rapid warming in May are the lead causes for this year’s abundance. That abundance reached as high as 63 percent above normal flow this spring, based on figures going as far back as 1981. Over the year, this will factor out to about 10 percent above normal figures.

While the dam is required by law to pass some water on for protection of marine wildlife, it also has to pass water downstream that is more than its turbine capacity. The U.S. Energy Information Administration also questions if a new court order may have increased the former’s limits at the dam. Traditionally, the required amount had been set at 40 percent of inflow, but the U.S. Army Corps of Engineers’ Fish Passage Plan saw required spill levels rise for the part of the season which ended June 15, leading to daily spill levels which ranged from 23 percent to 65 percent of daily inflow.