Allan Bisnett of the Community Covenant Church observed erosion by the Methow River behind the church. The river bank damage is threatening church property.
River bank has receded dramatically in past two years
If the Methow River continues to erode the river bank by the Community Covenant Church at the same rate as the past two years, a church-owned gazebo that is 25 feet away from the riverbank could end up in the river next spring.
Standing near the lip of the eroded riverbank, church treasurer Allan Bisnett said the Methow River — shallow and slow-moving this time of year — slammed into the bank “with tremendous force” during the spring runoff, tearing away the bank and large pine trees with it.
Bisnett said the church needs to take steps before snow falls to protect the gazebo and other church property from next spring’s high water. The bank has moved more than 35 feet closer to the church over the past two years. “We are in a position where we don’t want to wait to see what the next high water brings,” he said.
The church is located on a bend of the river, just off Highway 20 at the north end of Twisp. It faces the most imminent threat of property loss next spring, although several nearby residents have also seen the river erode the bank and carry away large trees in front of their homes in recent years.
“We’ve lived in this place 40 years, so we’ve watched the river for a long time,” said Debbie Francis, who lives with her husband, Jon, near the river, two properties downstream from the Community Covenant Church. “The whole river has changed its course. The last two years has been significant. It comes right at us at high water.”
The erosion, which also tore away a section of the newly built Twisp trail in the town park last spring, prompted Twisp Public Works Director Andrew Denham to pull together a brainstorming session at the River Bank Building in Twisp last week with about two dozen people from federal, state, municipal and tribal agencies, and impacted property owners.
After almost two hours of discussion, the group reached an informal consensus — the Community Covenant Church is pretty much on its own in protecting its property from high water next spring. Any project aimed at reinforcing the bank of the river would require permits from multiple agencies and require far more time and money than the church has at its disposal.
Increased erosion
The erosion in this stretch of river became especially apparent over the past two years, when the river reached unusually high spring runoff levels. Since 2009 the bank has eroded 83 feet of bank next to the church, and nearly half of that — 36 feet — has eroded since 2017.
At another bend in the river upstream from the church, erosion has taken 117 feet of bank since 2009, and 63 feet since 2017, impacting property owners on the other side of the river.
A study is getting underway this fall on this reach of the river, which extends about 2 miles upstream from the confluence of the Twisp and Methow Rivers at the Twisp Park. Near the top of the reach is a Okanogan County-owned levee, known as the “Sugar Levee,” that may contribute to changes in the river and resulting erosion, according to people at last week’s meeting.
The Bureau of Reclamation is conducting the study, which is aimed at evaluating hydraulic conditions in the main channel and side channels. The study’s primary purpose will be to guide fish habitat restoration projects, but it could recommend actions — such as altering or removing portions of the levee or modifying existing wood accumulations — that could also help property owners downstream. But the study isn’t expected to be completed until 2020, and that may be too late for the church or other property owners to avoid damage.
During discussion of possible short-term fixes to the erosion problem, participants in last week’s meeting concluded that any work done to reinforce the river bank would be far too costly and time-consuming, largely due to the extensive permits required for projects in salmon-bearing rivers and streams. And, because the church is a private organization rather than a public entity, funding from state or federal agencies would be unlikely.
The preferred solution by the end of the meeting appeared to be construction of what is termed a “buried dike” along the edge of the church property by the river. The project would entail digging a deep trench along the perimeter of the church property bordering the river and filling it with large boulders. The buried structure would hopefully stand up to the fast water in spring and hold the river back.
Without some protection in place, the river could continue eroding the property well past the gazebo, said Denham, perhaps reaching the church itself, an adjacent residence for the pastor, and potentially threatening Highway 20. “It is 340 feet from the Washington State Department of Transportation right-of-way to the current riverbank,” Denham said.
Bisnett said church officials are working with local engineer Fred Cooley to come up with a plan and approximate costs for the dike. Estimates range from $80,000 to $150,000 Bisnett said.
“Our little church doesn’t have the capability of paying that,” Bisnett said. “We will be going to the corporate level of Community Covenant Churches to see if they can help us. There will be some help locally, but not anywhere close to what we need.”
The Twisp church building is owned by the Community Covenant Church Corporation, and Bisnett said he believes church leaders won’t want to risk losing the investment.
Dynamic reach
The process that has led to the erosion on this reach of the river is complex, said Mike Brunfelt of Inter-fluve Inc. an Oregon company that specializes in investigations, design and restoration of rivers.
Brunfelt has previously studied this section of river and said it is the most “dynamic” reach of the Methow River. The section is an alluvial floodplain that over time has produced different channels as the river meanders through the relatively flat terrain.
“The rule is the channel moves,” Brunfelt said. The Sugar Levee, originally constructed in the 1940s and rebuilt in the 1970s, has likely altered the river’s course, he said.
“When the Sugar Levee got put in it pretty much blocked the river. If that weren’t put in, this channel would be lot different,” Brunfelt said. His analysis of the reach predicted a “migration range” for the river channel of 5 to 30 feet annually, which means erosion could be expected to reach those levels.
The levee was intended to protect Highway 20 and some downstream properties, said Chris Johnson of the Methow Salmon Recovery Foundation (MSRF). Almost 1,200 feet long, the levee has been identified in a biological opinion as “a likely problem for restoring salmon in that stretch of the river,” Johnson said.
The study, which is conducted by the Bureau of Reclamation, will examine the effects of the levee on loss of floodplain and increased river velocity, two factors that harm salmon spawning and rearing habitats. The study will also provide information about the impact of the levee on property owners, Johnson said.
“In a couple of years, we will not only have an idea what’s going on in that reach, we’ll also have resources that should improve conditions on these properties,” Johnson said.
Johnson said record high water the past two years exacerbated ongoing erosion in this stretch of the river. This past spring, the Methow River ran at nearly 20,000 cubic feet per second (cfs), considered a 50-year event, and the year before it reached 18,000 cfs, he said. “Those are what we call ‘bed changing’ events,” Johnson said.
Normal runoff levels are about 15,000 cfs, he said. “We went 16 years without a real high water, and then had two in a row,” Johnson said.
