DENVER (AP) -- Interior Secretary Dick Kempthorne signed a three-state agreement Thursday on managing the Platte River, capping years of efforts to resolve conflicts over use of the water.

Kempthorne signed the record of decision for the final environmental impact statement on a 13-year agreement among Wyoming, Colorado and Nebraska. All three governors must sign the agreement to implement the plan aimed at accommodating endangered species and the growing number of cities and farmers tapping the river that flows through the states.

"This recovery program is an outstanding collaborative effort among interest groups to cooperatively address the needs of endangered species and ensure that current uses of basin water can continue," Kempthorne said.

Negotiations on use of the Platte started in the early 1990s. Colorado, Wyoming and Nebraska signed an agreement in 1997 after the Fish and Wildlife Service said water projects on the river threatened vulnerable wildlife.

The plan calls for acquiring land for wildlife habitat in Nebraska and increasing river flows at key times. It will cost about $317 million, with $157 million coming from the Interior Department and the rest from the states in cash, land and water.

Congress must approve the federal government's portion.

The Platte River in central Nebraska is a major stop for migrating whooping cranes and home to the piping plover, least tern and pallid sturgeon. They're all designated as threatened or endangered species.

The U.S. Fish and Wildlife Service released a report in June saying the management plan is unlikely to jeopardize the long-term survival of the four species.

The river, with its 15 major dams and reservoirs, supplies water to about 3.5 million people, irrigates farms, generates electricity through hydropower plants and provides recreation and wildlife habitat. The Platte's two branches start in the Colorado mountains, flow through Wyoming and Colorado, and merge in Nebraska.