OKLAHOMA CITY - A federal mediator has been appointed in a federal lawsuit between two Oklahoma tribes and the state of Oklahoma.

The lead attorney for the Chickasaw and Choctaw Nations says Duke University law professor Francis McGovern will try to help the tribes reach a settlement with the state of Oklahoma and Oklahoma City of the usage of water in their historic area.

The tribes filed a lawsuit in August that seeks an injunction to bar the state and city from transporting water out of Sardis Lake in southeastern Oklahoma to central Oklahoma. At a conference in his chambers last month, U.S. District Judge Lee West said he intended to appoint a mediator to help resolve the dispute quickly and inexpensively.

The city of Oklahoma City says it is concerned the tribes could sell the water to entities outside of Oklahoma without regard to needs inside the state. The mediator is expected to study the issues and develop a plan that will satisfy all parties and stop the lawsuit from moving ahead.