Crooked River flows could fall to 10 cfs in September as drought persists

Even in times of drought, the amount of water flowing into the Crooked River from Prineville Reservoir typically hovers at or near 50 cubic feet per second. But this fall — after successive dry years and Crook County still in throes of severe drought — the flow is expected to drop to 10 cfs.The lower flow out of Bowman Dam will occur after irrigation districts in Crook County run out of water this year, said Gregg Garnett, Bend field office manager for the U.S. Bureau of Reclamation.As of Thursday, Prineville Reservoir was just 24% full. The reservoir this year had the lowest maximum fill on record dating back to the creation of the dam in 1961, according to the Oregon Water Resources Department. The lower levels mean less water for Crook County farmers to use on their fields, as well as lower levels in the river for fish to survive.Exactly when these low flows will trigger is up to the weather and water usage by irrigators. Hot temperatures like those expected next week will speed up the decline. Bruce Scanlon, manager for Ochoco Irrigation District, believes the district supply will be exhausted by late summer.“Crook County has been in exceptional drought for almost a year. It’s the only county in the state with this distinction,” said Scanlon.“Conditions have improved but we are still looking at irrigation water running out in early September.”Ochoco Irrigation District provides water to 898 patrons on 20,062 acres, mostly north and east of the Crooked River.Bridget Moran, the Bend field supervisor for the U.S. Fish and Wildlife, said her agency is working with Deschutes Basin Habitat Conservation Plan permittees and federal partners to “adaptively manage” the limited water supply in the Deschutes Basin. The permittees include eight irrigation districts in Central Oregon and the city of Prineville.Adaptive management allows the agency and irrigation districts to temporarily reduce reservoir outflows as needed in times of drought.“We are collaborating with the Bureau of Reclamation and our HCP permittees to come up with a solution that has the maximum benefit of all parties involved,” said Moran. “To provide the best conservation use of the limited water supply in the Crooked River this year, 10 cfs minimum flow is anticipated in September and October.”The winter — November to April — level of 50 cfs is a requirement of the Habitat Conservation Plan, which was finalized in 2020 after 12 years of development. During the rest of the year, the outflows from Bowman Dam are typically much higher due to irrigation needs. Due to drought this year there simply isn’t enough water to maintain higher levels.Prior to the conservation plan, there was a minimum release of 10 cfs from Bowman Dam.The flow of 10 cfs “is a requirement under the original federal legislation,” said Kyle Gorman, region manager for Oregon Water Resources Department. “It dates back to the 1950s when Congress was approving the authorization and legislation for building the Crooked RiverProject that is now known as Prineville Reservoir and Bowman Dam.”Moran says the winter flow of 50 cfs and spring pulse flows, created by snowmelt, will aid in the out-migration of anadromous smolts.“With a very limited water supply, (USFWS) are attempting to maximize benefits for those covered species with the water that is available,” said Garnett, the Bureau of Reclamation field officer.The intensity of drought in Oregon has waned in recent months thanks to a wet and cool spring, but many areas of the state remain bone dry.All of Crook County remains in extreme or exceptional drought conditions, according to the U.S. Drought Monitor.The Crooked River runs for 155 miles and the basin drains nearly 4,300 square miles. The river and its tributaries were once major spawning grounds for migratory fish, including spring chinook salmon, steelhead trout and Pacific lamprey. Redband trout and bull trout were also widespread.Dams and irrigation in the Crooked River basin built during the 20th century cut off access to spawning and rearing grounds, causing most of these species to dwindle in number from the river.Today, redband trout and mountain whitefish are found in the river, along with migrating and spawning adult spring chinook salmon. Bull trout have been seen using the fish ladder at Opal Springs and are using the lower Crooked River.Jerry George, a fish biologist with Oregon Department of Fish and Wildlife, said his agency is closely tracking reservoir levels, low stream flows, and warm water temperatures. Prineville and Ochoco reservoirs and the Chimney Rock Wild and Scenic section of the Crooked River downstream of Bowman Dam are of particular concern.“The situation is unprecedented, we have not experienced low flows in the tailwater reach below Bowman Dam during the irrigation season before,” said George. “This reach typically has an adequate volume of flow through the end of the irrigation season and cool water that is drawn from the bottom of Prineville reservoir. At this point, the scope of the impacts are unknown and difficult to predict.”A series of three canal piping projects costing $32 million could help Ochoco Irrigation District conserve water, leaving more water in the river for fish. These projects are planned for completion by March 2024 and will save the district 16.2 cubic feet of water per second, or about 7,271 gallons of water per minute.But some experts worry that the low flows combined with high summer temperatures could kill large numbers of fish before the conservation projects are completed. Salmonids like native redband trout are cold water species that need water temperatures generally below 68F.Amy Stuart, a retired fish biologist previously with ODFW, said redband evolved with occasional exposure to high water temperatures, but sustained high temperatures can cause chronic and acute distress leading to death.“Low flows can concentrate fish in pools and deplete oxygen,” said Stuart. “Fish in low warm flows are also much more vulnerable to predation and disease.”The U.S. Fish and Wildlife Service acknowledged the reality of the situation as it relates to steelhead and bull trout, two species of fish that use the Crooked River and are also covered by the Endangered Species Act.“During a period of severe drought, as we are experiencing now, water is limited,” said Moran. “This will provide the maximum benefit possible to the covered species with this limited water supply.”-Michael Kohn