LINCOLN, Neb. (AP) -- The long-standing dispute between Nebraska and Kansas over use of water from the Republican River is headed back to court.

The U.S. Supreme Court is allowing a special water master to again consider the case, and a three-week trial is scheduled to begin Aug. 13 in Portland, Maine, the McCook Daily Gazette reported (http://bit.ly/KT4N0t). Attorney William Kayatta Jr. will preside and help the high court decide the case.

Last year, the U.S. Supreme Court gave Kansas permission to file a new petition over allegations that Nebraska took more than its share of water for irrigation in 2005 and 2006 -- enough to supply a city of 100,000 people for a decade.

Kansas sued Nebraska over the Republican River in 1998. The two states settled the case five years later, but Kansas contends Nebraska violated the terms of the agreement.

Lawsuits among states over water are filed directly with the Supreme Court, which typically appoints a special master to review evidence and make recommendations to the justices.

Kansas wants to force Nebraska to reduce farm irrigation in its portion of the nearly 25,000-square-mile river basin and to pay Kansas back for the economic gains Nebraska allegedly received for using too much water. Kansas previously calculated the amount of the potential payment at $72 million, but is now asking for $50 million.

If Kansas prevails, Nebraska will be forced to stop irrigating 300,000 of the 1.2 million acres in its portion of the Republican River basin, causing farmers to rely on rain to grow crops.

Use of the Republican River's water is governed by a 1943 compact between Colorado, Kansas and Nebraska. Colorado was given 11 percent of the water, while Nebraska was allotted 49 percent and Kansas 40 percent.

In the 1990s, farmers and officials in Kansas accused Nebraska of surpassing its share. Officials in both states had hoped the 2003 settlement would end the dispute but acknowledged at the time that monitoring and enforcement issues remained.

Kansas officials contend that in 2005 and 2006, Nebraska used 25.7 billion gallons more in water from the Republican River than it was due.

An arbitrator appointed by the two states said in 2009 that Nebraska's natural resource districts should cut back on water allocations to farmers, a suggestion Nebraska rejected. But the arbitrator also recommended that Nebraska pay only $10,000 in monetary damages to Kansas.

Kansas officials contend that the non-binding arbitration was inadequate.