Hyrum Dam Spillway Replacement Project

Aerial view of the construction site at Hyrum Dam
Aerial view of the construction site at Hyrum Dam, June 2025. Reclamation photo

The landscape around Hyrum Dam is rapidly changing as construction is underway to replace the dam’s aging spillway. The new spillway, which will be built before the old one is demolished, is designed to safely pass high flows and withstand seismic activity—upgrading an original structure that no longer meets modern engineering standards.

Construction began May 2025, and is expected to take four years. As part of the work, the road atop Hyrum Dam (W 300 South) is closed and will remain closed until the project is complete. Detours are clearly marked, and Hyrum State Park remains open to visitors.

Project Facts
  • • 330,000 cubic yards of excavation
  • • 15,500 cubic yards of concrete
  • • 5.4 million pounds of reinforcing steel

Calendar

  • Nothing scheduled at this time

Detour Map

  • Road closure and detour map
    Click to view full screen

Announcements

  • News Release – June 24, 2025

    Aerial of the Hyrum Dam spillway replacement project site Landscape transforming as major spillway replacement project advances at Hyrum Dam

    HYRUM, Utah – Just weeks into construction, the landscape around Hyrum Dam is rapidly changing as a major construction project gets underway to replace the dam’s aging spillway. The $115.9 million effort will improve safety, boost resilience, and ensure reliable water deliveries for years to come. Read More »

  • News Release – May 19, 2025

    Road closed signHyrum Dam and Reservoir Road Closure – Public Notice

    HYRUM, Utah - The road atop Hyrum Dam, W 300 South, will be closed starting June 2, 2025, while crews construct a new spillway before demolishing the existing one. The road will remain closed to all traffic until construction is completed, which is anticipated to take 3 to 4 years. Road detours will be clearly marked. Hyrum State Park will remain open and can be accessed from S 400 West in Hyrum. Read More »

  • News Release – March 21, 2025

    The existing 90-year-old spillway is located left of the earth-filled dam.Reclamation awards $115.9 million construction contract for replacement of Hyrum Dam spillway

    SALT LAKE CITY — The Bureau of Reclamation today announced the award of a $115,900,000 contract to AMES Federal Contracting Group of Burnsville, Minnesota, for the construction of a new spillway at Hyrum Dam. Hyrum Dam was built on the Little Bear River in northern Utah in 1935 and impounds Hyrum Reservoir, which provides water storage for irrigation and municipal use. Read More »

  • UC Today article – Fall, 2023

    Provo's Force Account Crew made the repairs quickly to ensure the spillway could be used if needed as early as DecemberReady for the next go-round
    Repairs to Hyrum spillway completed after high water year

    The spillway at Hyrum Dam recently received needed and well-deserved repairs after record snowpack and high runoff this past spring pushed the nearly 90-year-old structure to its limits. During the peak runoff period (April - July 2023), spillway releases reached upwards of 1,100 cubic feet per second and about 90,000 acre-feet of water was released through the spillway – double the average of 44,683 acre-feet (2010 – 2022). Read More »

  • News Release – June 6, 2023

    Hyrum Reservoir filling for irrigation season Spillway is closed and no longer being monitored for safety

    SALT LAKE CITY – Reclamation today announced the closing of the spillway gates at Hyrum Reservoir, allowing the reservoir to fill for the irrigation season. With the spillway gates closed, the spillway no longer requires monitoring.

    Out of an abundance of caution, Reclamation began around-the-clock monitoring of the dam’s spillway early last month when high volumes of water had to be released from the reservoir through the spillway. Heavy equipment and riprap material were also staged nearby in preparation for potential emergency repairs. Read More »

  • News Release – May 2, 2023

    Water exiting Hyrum Reservoir through the radial arm gates and through the spillway.Reclamation continually monitoring Hyrum Dam spillway; ready to take action if needed

    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. Read More »

Last Updated: 6/25/25