BOULDER, Colo.—The federal government will impose a 10-year operating framework for managing water use in the Colorado River Basin by the end of this summer if the seven states that rely on the river cannot come to an agreement before then, said Scott Cameron, acting commissioner for the Bureau of Reclamation, at a water conference Thursday.

The announcement comes in the midst of the worst water year ever recorded on the Colorado River and after years of tense and largely fruitless negotiations between water managers in the states that rely on the declining waterway. The states have missed November and February deadlines to reach an agreement, and the current guidelines outlining drought mitigation efforts for the Colorado River Basin expire at the end of September, so new guidelines must be in place by Oct. 1.

State and tribal leaders, however, said the federal government’s proposal, which would be reevaluated every two years, will only lead to more uncertainty as it will require constant negotiations between the states over how to share the river, and could go against what some see as the guiding laws regulating the river.

In mid-summer, Cameron said, the Bureau of Reclamation will release the final Environmental Impact Statement, which will detail the federal government’s preferred plan for managing the river after 2026. The bureau will issue a final decision on the framework a short time later.