Hydropower facilities in the US face around ten times as many mandatory licensing conditions as they did under their previous licences, according to an analysis by the National Hydropower Association (NHA).

The association said the growth in requirements could affect the economic viability of existing projects as 348 Federal Energy Regulatory Commission (FERC) licences, representing 12,324MW of capacity, approach expiry between 2026 and 2036.

NHA’s report, Affordable Power, Broken Process, analysed more than 5000 mandatory conditions contained in 4819 licensing documents filed between 1980 and 2026. The documents covered 1642 FERC-regulated hydropower assets in 46 states and approximately 93% of active US hydropower licences.

The analysis used large language models, supported by human auditing, to identify the wording, responsible agency, statutory authority, type of work and stated cost associated with each condition.

Mandatory conditions are legally binding requirements imposed by federal resource agencies that must be incorporated into a project’s operating licence. FERC cannot reject or modify conditions issued under Sections 4(e) and 18 of the Federal Power Act.

NHA compared the current and previous licensing documents for 87 individual projects, separated by a median of 32 years. The earlier licences contained a combined 79 conditions, compared with 806 conditions in the more recent documents.

Across licences containing mandatory conditions, the number of Section 4(e) and Section 18 requirements in final licence orders has roughly doubled since 1986. The larger tenfold increase emerged when the same projects were compared with their own earlier licences, the association said.

The US Forest Service accounted for around two-thirds of the conditions examined. Together, the Forest Service, Bureau of Land Management, National Marine Fisheries Service and US Fish and Wildlife Service imposed 97% of the mandatory conditions identified.

Cost information was included in only 13% of Section 4(e) conditions and 6% of Section 18 fishway prescriptions. NHA said this could leave developers unable to determine the full financial implications of a licence.

Most projects also carried at least one “reservation of authority”, allowing agencies to impose additional requirements during the licence term. The report found that 82% of projects conditioned by the Forest Service contained at least one such provision.

Fish passage requirements were another focus of the analysis. NHA matched 71 projects subject to Section 18 conditions against Oak Ridge National Laboratory’s Fish Passage Database. It reported that targeted migratory species could not currently reach the dam at more than 40% of those projects and were absent from the entire sub-basin at nearly 10%.

The association argued that the burden falls disproportionately on smaller hydropower facilities because the number of conditions does not increase or decrease substantially according to project capacity.

An examination of 305 completed relicensing outcomes, comprising 112 licence surrenders and 193 relicences, found that each tenfold increase in capacity was associated with an approximately 78% reduction in the likelihood of surrender.

“I urge anyone who cares about reliable, affordable power to read this groundbreaking study,” said NHA’s President and CEO, Malcolm Woolf. “Hydropower, a superhero of the grid and an American icon of energy production, is at great risk due to a broken regulatory framework. Relicensing an existing hydropower facility often takes decades and costs millions of dollars. If these facilities go away, so does the affordable power they produce, the good jobs they create, and the critical infrastructure and ecosystem care they provide. NHA’s analysis of mandatory licensing conditions highlights a big part of this challenge and, perhaps most importantly, charts a path forward to unleash new hydropower resources.”

The US has approximately 80GW of conventional hydropower and 22GW of pumped storage capacity. According to the report, hydropower represents more than 80% of the country’s long-duration energy storage capacity and more than one-third of its blackstart-certified generating units.

NHA is calling on the Departments of Agriculture, Commerce and the Interior to limit mandatory conditions to the direct effects of individual projects and introduce a regulatory definition of “fishway”.

It also supports the proposed Hydropower Licensing Affordability Act, introduced in the House of Representatives as HR 9337 and in the Senate as S 5048. The legislation would require conditions imposed under Sections 4(e) and 18 to address the direct adverse effects of a licensed project.