HYTUM – As the weather warms up the need for water for the south end of the valley increases. When the flood waters on farm ground dries up and the planting begins water will be once again be flowing down ditches and sprinkler systems.
The spillway gates at Hyrum Reservoir were closed allowing the reservoir to fill with water for the upcoming irrigation season. The US Bureau of Reclamation announced with the closing of the spillway gates, the spillway no longer requires monitoring 24/7.
The Bureau began watching the dam’s spillway with around-the-clock monitoring early last month when high volumes of water were released from the reservoir through the spillway.
The South Cache Water Users Association and its 3500 shareholders are responsible for operating and maintaining the dam. The organization is working with the Department of Reclamation to replace the aging spillway soon.
If needed, heavy equipment and riprap material were standing nearby in case the spillway needed emergency repairs.
“We had a forecasted record runoff of 238% of average, requiring dam operators to pass a high volume of water through the spillway. Reclamation was prepared to take immediate action if the spillway, which is nearly 90 years old, needed emergency repairs,” said Reclamation Regional Director Wayne Pullan. “Fortunately, that didn’t happen. Now the reservoir is filling, and irrigation deliveries are being made to water users.”
This year the Reservoir’s projected runoff for April through July is 86,000 acre-feet, of which approximately 76,200 acre-feet has materialized so far this spring.
Recently, the reservoir’s elevation was measured at approximately 4667.5 feet and end-of-day storage was 12,468 acre-feet, leaving approximately 5.0 feet and 2,266 acre-feet (15%) of space remaining to be filled.
Inflows measured at the Little Bear River just above Hyrum Reservoir are currently decreasing.
Flows averaged 268 cubic feet per second a couple of days ago, which is the same as the previous day’s average. Flows of the Little Bear River peaked at 1,290 cfs in mid-May.
Hyrum Dam and Reservoir are the primary water storage for agriculture and are located on the Little Bear River, approximately nine miles southwest of Logan. The dam was constructed in 1935 to provide storage for irrigation and municipal uses.
Ongoing and continuous maintenance has been performed on the Hyrum Dam’s spillway at Hyrum Reservoir since its construction.
For more information about the spillway replacement project, go here.