Experts provide update on 2019 tunnel collapse and canal washout
In the months following the collapse of Tunnel Number Two on the Goshen-Gering-Fort Laramie main canal in July 2019, temporary repairs were made to Tunnel Numbers One and Two. Steel ribs were installed inside the tunnels to support the concrete walls.
The tunnel collapse and resulting washout of the supply canal south of Fort Laramie immediately ended water deliveries by Goshen and Gering-Fort Laramie districts for 44 days, during the critical growth period for crops. Approximately 107,000 acres were affected by the loss of irrigation water, and many farmers’ yields were reduced as a result.
The temporary repairs allowed the irrigation districts to resume deliveries in 2020, but installation of the ribs restricted water flow to 80 to 85 percent of capacity of the tunnel.
During the winter of 2020-21, metal sheeting was installed over the ribs to increase water flow through the tunnels. This increased the water flow through the tunnels to 97 percent of capacity in the summer of 2021.
Water deliveries by three major irrigation districts in the North Platte Valley – Goshen and Gering-Fort Laramie on the south side of the river and Pathfinder Irrigation District on the north – were near normal for the 2021 growing season.
The districts had to utilize storage water to meet the needs of the growers, leaving the reservoirs in Wyoming at lower-than-average carryover at the end of the water year. In mid-October, Seminoe Reservoir was at 31 percent, Pathfinder Reservoir was 58 percent and Glendo Reservoir was 32 percent of capacity.
For spring runoff to fill the reservoirs by the 2022 irrigation season, major snowfall events would be needed in the Snowy Range and Sierra Madre mountains of north-central Colorado and south-central Wyoming this winter.
Inspection of the tunnels by the irrigation districts and U.S. Bureau of Reclamation was scheduled for the week of Oct. 18. Permanent repairs to the tunnels still must be completed, with the final construction plans pending approval from the U.S. Bureau of Reclamation.
This article is courtesy the University of Nebraska-Lincoln Extension with contributions from Water and Integrated Cropping Systems Extension Educator Gary Stone, Extension Educator for Agricultural Economics Jessica Groskopf, Water and Integrated Cropping Systems Extension Educator John Thomas, Irrigation and Water Management Specialist Xin Qiao and Panhandle Research and Extension Center Communications Specialist David Ostdiek.