Saturday marked the formal transition to fall, officially ending one of the hottest and driest summers in Central Oregon history.
From July 1 to the end of summer, Bend received less than a fifth of an inch of rain, which made that period the fifth-driest on record, according to John Peck, meteorologist for the National Weather Service office in Pendleton.
Summer is often a dry time across much of Central Oregon, with an average of about an inch and a half of rain falling in Bend between July and September.
Still, the abnormally dry weather this year plunged the region further into drought, forcing irrigation districts to draw down local reservoirs and raising big questions about Central Oregon’s next irrigation season.
“It sure would be nice to get a really nice snowpack this (winter), and recharge a little bit,” said Kyle Gorman, south central region manager for the Oregon Water Resources Department, which oversees water use in the state.
As of Friday, Wickiup Reservoir, Central Oregon’s largest man-made reservoir, was 2 percent full, closer than it has been to emptying since 1952, according to Gorman. Wickiup Reservoir holds up to 200,000 acre-feet of water. An acre-foot is the amount of water necessary to cover an acre of land with a foot of water.
Gorman said that water levels in the reservoir are just 12 feet from what the Oregon Water Resources Department considers empty. The low levels make it nearly impossible for the reservoir to fill this year. If there’s another dry winter, irrigation districts operating in the basin could be forced to curtail their supply of water in 2019, Gorman said.
A dry winter has a more dramatic effect on water levels for irrigation than a dry summer does, but Central Oregon had both this year, Gorman said. Low snow totals, especially in the high country, left the Deschutes River Basin with less water than expected, and kept the underground flows in the area from being replenished, he said.
Bend received three-tenths of an inch of rain June 10, but since then, rain has been almost nonexistent. Since the start of July, all of the measurable rainfall in Bend fell on one day, Aug. 17, Peck said.
He added that a high-pressure system has been in place over much of the Western United States for weeks now, making it difficult for storms to form. Thunderstorms, a significant source of precipitation in Central Oregon during the heart of the summer, have mostly missed Bend this summer.
“I can recall maybe three or four days where we saw thunderstorms,” Peck said.
While Gorman said thunderstorms don’t have much impact on stream flows, they can keep crops irrigated for up to two weeks under certain circumstances, allowing farmers to turn off their sprinklers and temporarily stop drawing on irrigation water. Because those thunderstorms never came this summer, the demand for water from reservoirs was higher than it would be in an average year, Gorman said.
High temperatures this summer haven’t helped. While daytime highs and overnight lows have dropped over the past couple of weeks, June, July and August were each hotter than normal. So far this year, 28 days reached 90 degrees or warmer, the second-highest total in the last two decades, according to data from the weather service.
Central Oregon isn’t alone when it comes to seeing hot, dry weather this summer. According to the U.S. Drought Monitor, a map of drought conditions across the country produced jointly by several federal agencies, roughly 98 percent of Oregon is mired in moderate to extreme drought, with the only exception being a small sliver along the northeastern edge of the state.
While Central Oregon hasn’t seen many large fires near populated areas, that hasn’t stopped more smoke than usual from reaching the region. Greg Svelund, spokesman for the Oregon Department of Environmental Quality, said smoke from wildfires caused air to be unhealthy for sensitive groups on 12 different occasions during the summer, primarily during the middle and end of August.
Unlike last year, when the Milli Fire burning outside of Sisters made air throughout Central Oregon unhealthy for weeks, much of the smoke came from fires nowhere near Central Oregon, Svelund said. Large fires burning near British Columbia and near the Oregon-California border accounted for much of the smoke.
Svelund said the number of smoky days during the summer has risen in recent years, thanks in part to a growing number of large wildfires throughout the Pacific Northwest.
“To have 12 days over that standard, that’s a problem,” Svelund said.
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