The Dalles Dam drops to season low as Mid-C forwards continue to reach record highs

The Dalles Dam water supply forecast has reached a new season low after poor snow-building months and continued expectations of below-normal precipitation with much of the area is listed in drought conditions.

Power forwards in the Pacific Northwest are reaching record highs on concerns of above-normal summer temperatures and a weak hydropower outlook.

"We've had a declining water supply forecast throughout the spring season," David Bogema, US Army Corps of Engineers hydraulic engineer, said May 12 during the Columbia River Basin Water Management Technical Management Team meeting.

The Dalles water supply forecast for the April-September forecast period started the year strong at 96% Jan. 1. That eased to 94% by Feb. 1, and despite a slight rebound to 96% March 1, the forecast slipped to 92% April 1 and then sank to 86% by May 1, according to Northwest River Forecast Center data.

The Dalles Dam water supply forecast has fallen to 85% of normal for the April-September forecast period, a drop of 20 percentage points year on year and the lowest level in 16 months, according to Northwest River Forecast Center data.

Inflows at The Dalles Dam were 224.1 kcfs May 11, down 17% year on year, while generation at the The Dalles Dam was 744 MW May 4, also down 17% year on year, according to US Army Corps of Engineers data.

The below-normal water supply outlook translates to less hydro generation availability during the summer peak season.

Hydro-powered generation is the lead fuel source in the region, averaging more than 70% of the total fuel mix annually for the last five years, according to Bonneville Power Administration data. Hydro generation has grown from 70% of fuel mix May 1 to 96.3% May 11, an 11-month high, as wind generation dropped from 17.4% May 1 to 1.4% May 11, according to BPA data.

Power prices peaking

In reaction to the low hydro forecast, Mid-C on-peak forward summer packages are the highest in history, averaging about 200% above where the prior five years summer packages averaged.

Mid-C on-peak August is in the mid-$140s/MWh, 230% higher than the five-year average and 261% above the 2020 package, according to S&P Global Platts data. Likewise, on-peak July is in the low $120s/MWh, 223% above the five-year average and 258% higher year on year, while on-peak June is in the low $50s/MWh, 146% higher than the five-year average and 215% above the 2020 package last year.

Similarly, Mid-C on-peak day-ahead prices have risen to the low $50s/MWh for May 12 delivery, up 119% from the beginning of May and 135% above the year-ago average, according to Platts pricing data.

In near-term packages, Mid-C on-peak balance-of-the-month has risen 31% from the beginning of the month to the low $40s/MWh for May 11 trade date, compared to around $10/MWh a year ago, according to Platts pricing data.

The three-month outlook continues to indicate a greater probability for below-normal precipitation across the Pacific Northwest, according to the US National Weather Service.