Mitigation study for ice jam flooding approved

WORLAND — Washakie County’s ice jam flood mitigation proposal is one of 10 pilot projects selected in the northern region for study.

Washakie County Homeland Security and Emergency Management Director Jeff Schweighart said the funding for the project was approved through the Water Infrastructure Act of 2018, recently signed by President Donald Trump.

The U.S. Army Corps of Engineers has selected two sites on the Missouri River watershed system — Miles City, Montana, and Worland, Wyoming. Schweighart said too often, due to population requirements, projects that are selected are in the northeast region.

Following the ice jam flood in 2017, city and county officials have been working toward finding short-term and long-term solutions. The short-term solution was removal of the sandbar north of the Big Horn Avenue/US 20 bridge in the fall of 2017. The long-term solution has been for a feasibility study on mitigation projects.

Both the short- and long-term solutions began following the 2017 flood event. Immediately following the event, city and county officials met with Wyoming Homeland Security Director Guy Cameron on a teleconference call with Army Corps of Engineers in the planning division in Omaha, Nebraska.

The immediate plan for the removal of the sandbar was launched at the meeting.

In October 2017, 16,000 cubic yards of sediment was removed from the Big Horn River just north of the U.S. 20 bridge.

Washakie County Commission Chairman Terry Wolf testified before a U.S. Senate committee regarding the ice jam flooding. The hearings by the Environmental and Public Works Committee, chaired by Sen. John Barrasso, were for the Water Infrastructure Act.

Following the hearings, Schweighart began work with the Army Corps of Engineers on submitting a project for a feasibility study to look at long-term mitigation solutions.

“We solicited approval to be one of the 10 pilot study areas for ice jam mitigation proposals. It was approved pending funding,” Schweighart said. That funding was granted Oct. 19, 2018, by the Army Corps of Engineers.

“This is like winning the lottery, to be one of the 10 pilot study areas,” Schweighart said.

“Mitigation is the proactive actions completed to detour a future risk or hazard, in this case it is the ice jam build up and the following flooding. Mitigation is an ongoing commitment to realize an effective long-term success,” he said.

With funding approved, the next step is for the Army Corps of Engineers to select a project manager. Schweighart said he expects that to happen within the next week or two. Then a team of technical staff will be onsite at the Big Horn River, which he hopes will happen within the next month.

A kick-off meeting with county and city officials will then be scheduled, likely in early 2019, Schweighart said.

While the funding has been approved, Schweighart said it is a 50-50 project. He said he hopes that mitigation work that has already been completed, including removal of the sediment bar, can be considered as part of the match.

The feasibility study will look at economics, including cost of mitigation efforts already completed and what proposed projects may cost. It potentially could also look at flood plain management, hydrology, sediment sources and agency permitting protocols.

The kick-off meeting will determine the scope of the study. The meeting, combined with the onsite visit, will help determine the cost of the study, Schweighart said.

Schweighart said potential outcomes of the study could include:

•Use of jetties to clean out sandbar formation by the Big Horn River’s natural hydrology and energy to detour future mechanical removal in island buildup.

•Survey study of sediment source that could call for reservoir maintenance, cleaning out fill or breached dam repairs on 15 Mile Creek tributaries.

•Possible replacement of the loss of the electronic gauge that was taken out of serviced July 1 due to lack of funding. The gauge provided river levels at the bridge. Schweighart said in the interim he is working on providing a physical gauge to be able to monitor the river for the spring and summer 2019.

•Long-term proposal could include a federally-approved berm on the northeast of the embankment of the river as a protection measure, similar to what the Town of Greybull has in place.

Schweighart said the study could also reveal something that has not yet been considered, or reveal something else that may be a contributing factor in cause and effect of dealing with the ice jam flooding.

Funding for construction of any of the mitigation projects following the study would be a 65-35 match, Schweighart said.

“What makes this project more promising is the great private landowners to work with, and effective collaboration of city and county and other agencies including the Washakie County Conservation District and Natural Resources Conservation Agency, and the competent local contractors we have as was proved on the sandbar removal project,” he said.

“It’s a very unique opportunity for our community for both near and long-term prevention and protection measures for floodplain management,” he said.