Washington ? The Supreme Court would become a water-management agency if the state of Kansas has its way, a Colorado attorney argued Monday in the decades-old dispute over the Arkansas River.

The high court has already resolved the central legal issues in the case. Justices ruled in 1995 that Colorado diverted millions of gallons of Arkansas River water to its farm fields, taking water that should have gone to Kansas and violating the Arkansas River compact.

In 2001, the Supreme Court ordered Colorado to pay millions of dollars in damages and interest for depleting the river — although not as much as Kansas wanted.

Kansas officials returned to the court on Monday, asking for $24 million more in interest than the court-appointed special master recommended.

Kansas also is seeking changes in how the compact, which governs how the states use water from the river, will be enforced. For example, Kansas is asking the court to appoint a river master to decide how much water to release each year.

The lawyer representing Colorado, David Robbins, cautioned that the court would “become a super water-management agency for the country” if justices grant Kansas’ request.

A river master, like an arbitrator, would carry out the court’s decree, and his or her decisions would be harder to appeal.

Appointing a river master would be unusual for the high court, which has taken that step in only two other cases: a fight between Texas and New Mexico over the Pecos River and a battle among Pennsylvania, New Jersey and New York City over the Delaware River.

Kansas Atty. Gen. Phill Kline thought the justices seemed skeptical of the river master idea. Kline did not argue the case — that job was done by John Draper, a special assistant to Kline — but was in the courtroom with other attorneys involved.

“I thought the court hesitated, just in the context that they don’t want to keep dealing with it,” Kline said in an interview afterward.

But Kline was encouraged by the court’s reaction to another request by Kansas: to use annual measurements, instead of a 10-year average, to determine Colorado’s compliance with the compact.

It’s vital to Kansas farmers that water promised under the compact be delivered each year, Draper said in arguing for Kansas.

The debate over money concerns interest on damages Colorado owes to Kansas. Kansas is asking for $53 million, while Littleworth recommended $29 million.

Regardless of what the court decides, Kline said, the litigation is more about water than money.

“As you apply this compact in the future, we are getting hundreds of thousands of acre feet of water that would not have come to Kansas” without the Supreme Court’s earlier ruling, he said.

An acre foot is the amount of water one foot deep covering a flat acre of land.