SALT LAKE CITY – Because of record snowpack and projected record high runoff into Hyrum Reservoir, the Bureau of Reclamation is conducting around-the-clock monitoring of the spillway at Hyrum Dam, as operators are releasing a high volume of water through the spillway to help manage the reservoir’s water level as warm temperatures have significantly increased snowmelt and runoff into the reservoir.
“The spillway has served us well for 90 years, but because of its age and because it lacks the features of a modern spillway – and out of an abundance of caution – Reclamation has worked quickly to stage heavy equipment and riprap material near the spillway, in case we need to take immediate action,” said Reclamation Regional Director Wayne Pullan.
Hyrum Dam and Reservoir are the water storage features of the Hyrum Project. The dam and reservoir are located on the Little Bear River, approximately nine miles southwest of Logan, Utah, in the northern part of the state. The dam was constructed in 1935 and provides storage for irrigation and municipal use.
Low-volume water releases from the dam’s spillway started in December to minimize the risk of flooding. However, above-average snowpack and a forecasted record runoff of 238% of average are now requiring high flows from the spillway.
“Dam operators are balancing the reservoir’s inflows and outflows to avoid putting unnecessary stress on the spillway,” said Pullan. “We’re using all the tools and taking all the precautions we can now to manage the ongoing high flow of water at Hyrum—as we are at all our Utah facilities.”
In addition to continuously monitoring the spillway, Reclamation staff are closely tracking hydrology and weather forecasts. Since temperatures started to rise in late April, spillway flows have reached more than 1,000 cubic feet per second. Temperatures are forecasted to decrease in the next few days and stay lower into next week, which may help slow the runoff coming into the reservoir and allow dam operators to decrease flows from the spillway. Dam operators will likely continue using the spillway until mid-June, and it’s likely the spillway will have to convey high volumes of water during that time. Flows of the Little Bear River just above Hyrum Reservoir can be monitored here: Little Bear River at Paradise, UT - USGS Water Data for the Nation.
Ongoing and continuous maintenance has occurred on the spillway since construction. The South Cache Water Users Association, which is responsible for operating and maintaining the dam, is working with Reclamation to replace the aging spillway in the near future. For more information about the spillway replacement project, visit: https://www.usbr.gov/uc/provo/index.html.
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The Bureau of Reclamation is a federal agency under the U.S. Department of the Interior and is the nation's largest wholesale water supplier and second largest producer of hydroelectric power. Our facilities also provide substantial flood control, recreation opportunities, and environmental benefits. Visit our website at https://www.usbr.gov and follow us on Twitter @USBR; Facebook @bureau.of.reclamation and @coloradoriverbasin; LinkedIn @Bureau of Reclamation; Instagram @bureau_of_reclamation; and YouTube @reclamation.