Water is pouring into Prineville Reservoir at rates not seen since 2017 and pouring out of Bowman Dam nearly as quickly, as the massive snowfall from February begins to melt more rapidly.
As of Monday morning, roughly 4,000 cubic feet per second of water were flowing into Prineville Reservoir, significantly more than usual for this time of year, said Kyle Gorman, region manager for the Oregon Water Resources Department.
In response to high flows, the U.S. Bureau of Reclamation announced it increased outflow from Bowman Dam to 2,500 cubic feet per second Monday afternoon. But Gorman said he still expects Prineville Reservoir to fill by the heart of irrigation season.
Gorman said the Crooked River just above Prineville Reservoir saw a sharp uptick in flow around March 18, once warmer temperatures and rain in high-elevation portions of the Ochoco National Forest caused the snow in the area to start melting. Consequently, levels at Prineville Reservoir have surged toward average over the past three weeks, and Gorman said he expects the trend to continue.
“The rivers are going to be cold, swift and deep,” Gorman said.
After a dry start to the winter, a series of winter storms blanketed Oregon with snow in February, shattering records for snowfall during that month.
The wet, cold month shifted the narrative in Oregon statewide, turning what was shaping up to be a below-average snow year into a boon for the state.
“February basically saved our butt,” said Kurt Moffitt, soil survey office leader for the Natural Resources Conservation Service’s Redmond office.
While the storms helped snowpacks across the state, Moffitt said some areas benefited more than others. By and large, southern and eastern portions of the state fared proportionally better than the northern Cascades, which get more snow in a typical year, Moffitt said.
That was the case in Central Oregon as well. Moffitt said most sites in the Central Cascades where the NRCS collects snow-level data are average to slightly below-average for this point in the season. By contrast, the snowpack feeding the Crooked River sits at 153 percent of normal as of Monday, according to Julie Koeberle, snow hydrologist for the NRCS Portland office.
Moffitt added that high-elevation portions of the Ochoco Mountains tend to behave more similarly to mountain ranges in the eastern half of the state than they do to the Cascades, and are less influenced by coastal weather patterns.
“West to east across the Ochocos, it tends to get wetter as you go east,” Moffitt said.
As the weather has warmed and brought spring rains, that snow high in the mountains has begun to melt, which Gorman said has brought good news for Prineville Reservoir and the farmers who rely on it. Thanks to a dry 2018, Central Oregon’s second-largest reservoir had been drawn down to dangerously low levels, and was well below average as of the beginning of March.
The melt-off has allowed those levels to surge past where they were at this point last year, according to data from the Bureau of Reclamation. While Moffitt cautioned that too much warm weather could still cause the runoff levels to drop below normal, Gorman said the combination of a full reservoir and a flowing river should provide farmers with plenty of irrigation water, and may allow the reservoir to begin next year at higher levels than it did last year.
“This year, we should have much better carryover,” Gorman said.
While trout and other fish living in the Crooked River may benefit from having cool water released from Bowman Dam, the dam poses other problems for them. Tim Porter, assistant fish biologist for the Oregon Department of Fish and Wildlife, said the turbulence in the discharged water can saturate it with nitrogen, which can harm trout, salmon and other fish.
Porter said the illness, known as gas bubble disease, is common during significant water releases from Oregon dams, and typically begins affecting fish when discharges exceed 1,200 cubic feet per second.
“It can kind of give fish the bends,” Porter said.
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