The Association of State Dam Safety Officials says in a new report that the overall cost of upgrading dams that the federal government does not own or operate more than doubled over the past year, to $157.5 billion, from $75.7 billion in its 2022 report. 

The ASDSO also says that the 2023 total includes $34.1 billion to upgrade "high-hazard" dams, which have the potential to lead to loss of life if they should fail. That figure compares with $24 billion last year. There are more than 88,600 nonfederal dams.

Among the factors behind the sharp jumps in the estimates are a "more refined" cost-estimating methodology, including a dam's age and condition assessment; and a more refined dam-height category; and updates that reflect wider scope and breadth of engineering studies and also reflect higher construction materials and labor costs.  

The report also states, "Costs will continue to rise as maintenance, repair and rehabilitation work is deferred."

To address the climbing costs, the ASDSO calls for additional investment. The association acknowledges the help for dam rehabilitation in the 2021 Infrastructure Investment and Jobs Act. It pegs IIJA dam-rehab-related funding at more than $4 billion. 

But the association says that more is needed.

Sharon K. Tapia, manager of the California Dept. of Water Resources division of safety of dams, said in a statement“To ensure the safety of our nation’s dams, we must maintain high funding levels to address the thousands of dams needing rehabilitation.”

Tapia, a member of the ASDSO’s task force that produced the report, said, “We cannot return to previous funding levels," which she says are typically less than 1% per year of the dam allocation in the IIJA.

Congress has provided some help in recent years. In 2016 lawmakers added to the Federal Emergency Management Agency's National Dam Safety Program a grant program to address high-hazard dams. 

According to the report, congressional lawmakers have authorized as much as $60 million a year for the high-hazard grants. That program received a $585-million boost in the IIJA.

ADSDO says that in developing its national cost estimates, it used data based on actual costs of more than 500 dam rehabilitation projects that range from $10,000 to more than $500 million. Officials looked at projects over the past 10 years and "known upcoming projects." The information included dam heights, ages and condition assessment ratings.

The association notes that the federal government owns or regulates only 5% of dams in the U.S.; about 31% are owned by federal, tribal, state or local governments. Roughly 65% are privately owned.