Repairing, removing man-made obstructions
By Ann McCreary
Four miles up the Twisp River, work is underway to undo a century of man-made changes to the river at the site of the former Methow Valley Irrigation District (MVID) diversion.
The Methow Salmon Recovery Foundation (MSRF) is leading a project designed to restore habitat for fish and wildlife, now that MVID will no longer take water from the river for irrigation.
The “Twisp River Floodplain Project” involves altering a large levee, removing a massive concrete fish screen structure, re-establishing wetlands, and restoring native vegetation on about 20 acres around the former irrigation diversion.
“Methow Salmon Recovery Foundation acquired the property about four-and-a-half years ago, but discussions with MVID about the site has been going on for probably close to a decade,” said Chris Johnson, MSRF executive director.
Since the 2004 reconstruction of the fish screen, which prevents fish from entering the irrigation canal, MSRF began looking ahead toward repairing the human disruptions to the area, Johnson said. The property is located about 4 miles from the mouth of the river, off Poorman Creek Road.
MVID has been withdrawing water from the Twisp River since the early 1900s. The district has been embroiled in years of legal and regulatory battles with state and federal environmental agencies, because the diversion harmed habitat for threatened and endangered fish in the Twisp River.
“It was clear that the diversion was taking too much water and needed to reduce the amount,” Johnson said. “The writing was on the wall. We didn’t know how it was going to end, but we knew it would.”
This irrigation season was the last time MVID will take water from the Twisp River. The district has reconfigured its delivery system so that members who previously irrigated with Twisp River water will use groundwater piped from four large wells dug this year behind Hank’s Harvest Foods, or from individual wells on their property.
The Twisp River provides habitat for three species of fish that are protected under the federal Endangered Species Act. Spring Chinook, listed as endangered, and steelhead, listed as threatened, use the river for spawning and rearing. Bull trout, listed as threatened, use the river for foraging, migration and over-wintering.
Work to restore the river to its pre-diversion condition began last month, with heavy equipment lowering a portion of a levee that was constructed in the 1970s by the Army Corp of Engineers to protect MVID’s diversion structures.
The levee extends about 700 hundred feet along the riverbank above the intake canal that channeled water from the river into MVID’s ditch. The levee does a very efficient job of cutting the river off from adjacent flood plains, and helps accelerate the flow of the river downstream — neither of which is good for fish, said Brian Fisher, project manager.
About half of the downriver portion of the levee has been lowered as part of the project, to allow the river to flow over the top at high water. Next summer, the levee will be breached in two locations to allow the river to flow through and connect to adjacent wetlands, except during the lowest water levels.
Standing on the levee during a recent visit to the project site, Fisher pointed out a channel created by MVID to direct water from the main stem of the river toward the intake. It was at this location that MVID would bring an excavator into the river each summer, with permission from state environmental regulators, to create a temporary dam to direct water toward the intake.
In past years the district diverted as much as 30 cubic feet per second (cfs) from the river, Fisher said. “Two weeks ago the Twisp River flow was 44 cfs. If you’re taking 30 that’s darn near all of it. It’s not good for fish from a fish biologist’s standpoint,” he said.
Good for fish
The breaches in the levee will be created next July. To avoid harming fish, that is the only time of year that construction equipment is allowed into the river, Fisher said. The MVID headgate structure in the river will also be removed in July.
Reconnecting the river to the historic flood plain “does a lot of good for the river and for food webs. And by supporting food webs, it helps fish do better and creates habitat for steelhead and spring Chinook,” Fisher said.
The breaches are designed to maintain a connection to the river and provide a backwater alcove for fish, rather than a flowing channel, Fisher said.
Last month the large fish screen structure was demolished and the concrete and metal hauled away. The old MVID canal from the headgate leading toward the screen was contoured to create a more natural channel that will continue to flow from the river. Where the fish screen stood, a network of slow moving channels will be re-established or created in the flood plain to provide refuge to fish and allow them to make their way back to the river.
Fisher said he expects the channels to change naturally as water flows through the flood plain. “Mother nature does a better job of creating habitat than humans,” he said.
Project workers planted about 300 trees and shrubs along the sides of the former canal route, and an adjacent access road will be eliminated and restored to a natural state by the end of the project.
The Twisp River Floodplain Project will cost about $2.1 million when completed in 2016. About half the funding comes through Bonneville Power Administration for fish mitigation, with additional funding from the Bureau of Reclamation and the Washington Recreation and Conservation Office.