Restored wetland near Dillon Falls gets water
五月 10, 2016
Federal officials returning Ryan Ranch area to original stateBy Hilary Corrigan / The Bulletin
Federal agencies have started filling an open, grassy area near Dillon Falls like a bathtub.
“If all goes well, this will all be underwater,” said U.S. Fish and Wildlife Service Field Supervisor Bridget Moran.
About 65 acres of flood plain on the Deschutes River, Ryan Ranch was privately owned until the 1940s when the U.S. Forest Service got it in a land exchange and leased it as a cattle ranch until 1989. Since about the 1920s, it has been disconnected from the river by a berm.
“They took it from wetland to a dry-farming meadow, and now we’re trying to bring it back,” Moran said.
Forest Service officials say that under its natural conditions, the river would feed the area with water when it rises and take water from it when levels fall. But management of the river’s flow for irrigation has helped make the river’s levels very low in the winter and very high in the summer. Those flows, along with the berm blocking the water from the land, has helped erode the river’s banks.
The goal of the project is to reconnect the river to the flood plain, restoring the natural connection between the wetland and the river — the way they feed one another — and restoring about a third of a mile of badly eroded river banks, said Jason Gritzner, a hydrologist with the Deschutes National Forest.
“We’re not, obviously, fixing the flows with this project,” Gritzner said.
The project involves piping water from the river to the wetlands for stretches of time and will later entail removing the berm and re-establishing vegetation. If part of the site drains water quickly, that section can be isolated and restoration work can continue in the other parts.
“This is still filling up,” Gritzner said, as water bubbled from the Deschutes River through the pipes that run under a berm and into the site.
The Forest Service plans to keep the pipes open for about another month as the river continues rising, then close the pipes to see what happens without input from the river. That process of opening and closing the pipes will repeat later in the summer to see what happens — if the water level drops quickly or not.
“The trend’s been good,” said Deschutes National Forest soil scientist Peter Sussman. The surface water has spread from 15 acres to 35 acres since mid-April, and Sussman wants to see the full 65 acres fill with water, with depths of about 3.5 feet.
“We know that this landscape can hold water,” Gritzner said, noting the soil and monitoring wells that have checked water levels. “We know it has the capability to hold water.”
Monitoring will continue through the winter, and after determining the level of restoration that will occur, the agencies will take out the pipes, remove the berm and lower the river banks.
“We expect to see water year-round here,” Gritzner said.
U.S. Fish and Wildlife Service biologist Jennifer O’Reilly noted that when the land fills with water, a whole food base forms for animals like cranes.
“You’re gonna have a whole smorgasbord,” O’Reilly said. And the chances are good for the Oregon spotted frog to use the site; it needs to spend its whole life in water, and a population of the frog — listed as threatened under the Endangered Species Act — is known to be at a site nearby.
“I can’t wait to see what pops up here,” O’Reilly said. “Maybe toads, salamanders.”
Cranes and ducks already visit the site. Gritzner expects various animals to forage for food and rear their young there. Birds could stop by while migrating, followed by their human observers.
“The bird-watchers are gonna love this place,” Moran said.
Gritzner is also interested to see the types of vegetation that arise — possibly willows and tules, a tall marsh plant.
“We haven’t seen that here in decades,” he said. And he expects the site to benefit the river’s water quality as it returns water to the river.
“Wetlands are kind of a natural filter for water on the landscape,” Gritzner said.
The project aims to see whether the site, long cut off from the river, can still hold water like a sponge and function as a wetland.
“That’s sort of what the test is all about, to prove that,” O’Reilly said.
The project uses a limited license held by irrigators to account for and measure the water used. That permits the Forest Service to use the water on a limited basis, from some of the water that irrigation districts use, Gritzner said.
Craig Horrell, district manager of Central Oregon Irrigation District, noted the project marks the first such restoration effort in the Upper Deschutes and could serve as a model.
“This will give us the road map for other projects,” Horrell said, noting that it offers a chance for the different agencies, irrigation districts and other groups to work through such issues as water rights. “We’re gonna learn what everyone’s hot buttons are.”
Eric Beck, a seventh- and eighth-grade science teacher at Rimrock Expeditionary Alternative Learning Middle School, has brought his seventh-grade students out to monitor the site for five years. They check soil types and moisture levels, the density of different tree species and other conditions. They also write about the site, do artwork on it, graph their collected data in math class and learn how to display it — then try to make sense of patterns they see.
“(We’re) trying to think holistically about that whole ecosystem,” Beck said, noting students’ excitement about the wetlands restoration work that has begun.
Scientists expect others to also enjoy it.
“Sixty-five acres of wetlands as a freshwater marsh habitat are invaluable to a lot of species,” Sussman said, pointing to aquatic, avian and mammalian species that use wetlands. “And here we are, finally seeing it like we would 100 years ago.”
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