The Dalles Dam water supply forecast has fallen to the lowest point of the season with the weather outlook not indicating any relief in the months ahead.
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Summer forward packages surged 225% as a result.
After a strong start to the year, March and April brought a steady decline in the water supply forecast across the Pacific Northwest region, hydrologist Henry Pai said May 6 during the monthly Northwest River Forecast Center water supply briefing.
"The past couple months have been very dry as far as what's falling out of the sky and that's brought the seasonal precipitation down across the basin," Pai said.
While May is typically the last monthly water supply briefing, the NWRFC has scheduled a June 3 call because of seasonal conditions.
The Dalles Dam water supply forecast is at a 15-month low 86% of normal for the April-September forecast period, according to NWRFC data. That is a drop of 5 percentage points month on month and 14 percentage points below year-ago levels.
Currently, The Dalles is sitting below the 2020 trend line, which was also below normal. "Essentially, two consecutive water years trailing below normal conditions," Pai said.
The year-to-date adjusted runoff for The Dalles is 80% of normal, down 2 percentage points month on month, Pai said.
Inflows at The Dalles Dam averaged 134.98 kcfs in April, 36% below the three-year average and 9% lower year on year, according to the US Army Corps of Engineers.
Generation at The Dalles Dam averaged 563 MW, 32.3% below the three-year average and 7.2% lower year on year, after dropping 72% day on day to 436 GW April 20 because of the start of mandatory spring spill, Morris Greenberg, S&P Global Platts analytics managing director of North American power, said in a May 3 email.
With dry weather and snowmelt currently underway, the water supply forecast has dropped significantly across much of the basin in the Pacific Northwest. As snow melts, it feeds into reservoirs along major rivers in the region where hydropower is generated.
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 and reaching as high as 98% in May 2019 during a strong water year, according to Bonneville Power Administration data. Excess power from the Pacific Northwest is exported to neighboring regions, such as California.
"The snowpack acts as our natural reservoir in the Northwest," Pai said.
Snowpack had healthy conditions at the end of March, holding onto the cold, but had large changes in April with most of the region below normal, Pai said.
Monthly temperatures were below normal in February but rose to above-normal levels by April, Pai said, adding precipitation levels were mixed in February but fell to below-normal levels by April.
"Essentially, most of our basin is below normal," Pai said about the water year-to-date precipitation levels.
The six- to 10-day and three-month weather outlooks indicate a greater probability for below-normal precipitation across the Pacific Northwest, according to the US National Weather Service.
The below-normal water supply outlook translates to less hydro generation availability during the summer peak demand season, which is driving up power forwards.
Mid-C on-peak June is in the mid-$40s/MWh, 179% above the 2020 package a year ago, according to S&P Global Platts data.
The on-peak July package is in the mid-$110s/MWh, 231% higher than its 2020 counterpart, while on-peak August is in the mid-$130s/MWh, 242% higher.
The August 2021 package is trending well above all previous years, reaching record levels, on concerns of weak hydro supplies as the region is already experiencing drought conditions with red-flag warnings issued earlier than normal.