HYRUM – Construction of a new, much needed spillway on Hyrum Dam was announced earlier this week by the U.S. Bureau of Reclamation. Construction will begin later this year. The Bureau awarded a $115 million contract to AMES Federal Contracting Group of Burnsville, Minnesota, for the construction of the new spillway.
A photo of the spillway in need of repair at Hyrum Dam supplied by the US Bureau of Reclamation.
Wayne Pullan the Reclamation Upper Colorado Basin regional director said, “The spillway at Hyrum Dam is used every year to release excess water downstream, and though continuous maintenance has occurred on the spillway since its construction, the 90-year-old structure is in need of replacement.”
The dam’s original 24-inch outlet is being replaced with larger, 36-inch piping, allowing quadruple the outlet’s discharge capacity from 50 cubic feet per second (cfs) to 200 cfs.
“Working with our project partners, Reclamation will continue to take every precaution at Hyrum Dam,” said Provo Area Office Manager Rick Baxter. “That includes our current work to expand the size of the dam’s outlet works so more water can be conveyed through the outlet and alleviate additional stress on the existing spillway until a new one is built.”
He said construction should last about three years.
“We are enlarging the channel for the now to minimize the use of the spillway while the new one is under construction,” Baxter said. “When the new spillways is complete, it will be a similar design it will look somewhat same.”
The funding for the construction is secure, it falls under the safety of dams funding.
“It has to be approved by Congress and should not be under scrutiny by the current administration,” he said. “We hope the construction will begin in June.”
The South Cache Water Users Association (SCWUA) is responsible for operating and maintaining the dam.
The Reclamation press release said over the years, the SCWUA has done their best to minimize the amount of water released through the spillway. When spillway releases reached high volumes in the past few years, Reclamation performed around-the-clock monitoring to assess risks of spillway failure and staged heavy equipment and riprap material near the spillway in case immediate action was needed.
Construction on the dam began in 1934 and was completed in 1935. It was built as a rolled earth and rockfill structure containing 352,000 cubic yards of earth fill, 62,000 cubic yards of rockfill, and 13,000 cubic yards of riprap and gravel blanket, for a total of about 430,000 cubic yards of material.
The Hyrum Dam was built on the Little Bear River and impounds a total capacity of 18,685 acre-feet of water storage for irrigation and municipal use.
The dam has a surface area of 480 acres of water used for irrigation by the South Cache Water Users Association and is also used for recreation and fishing.
Work being one at Hyrum Dam to replace the 24 inch pipe with 36 inch pipe to increase the water discharge capacity.
The first water was made available later that year in July 1935.
The Little Bear River has a history of being a prime area for early trappers.
General William H. Ashley, a trapper, stopped near what is now the edge of Hyrum Reservoir and cached $150,000 worth of furs, mostly beaver, in the winter of 1825-26.
Ashley stored his furs in a cave dug in a clay bank until they were retrieved the following summer. This history resulted in the French-Canadian name of Cache Valley and Cache County.