The Tarrant Regional Water District's lawsuit against two Oklahoma water agencies was supposed to be a negotiating tool of sorts during pursuit of permits to buy water from river basins in the southern part of our northern neighbor.Five years later, the feud is before the U.S. Supreme Court, which will determine the course of the meandering litigation.The justices are expected to consider the water district's petition at a private conference March 23, and the parties could know the next week whether the court will set arguments for fall or Oklahoma will have succeeded in blocking out-of-state water sales.The Tarrant district has been largely unsuccessful in using the suit to facilitate its acquisition of water under the Red River Compact, among Texas, Oklahoma, Arkansas and Louisiana.Federal trial and appellate courts have ruled that the compact doesn't prevent Oklahoma lawmakers from passing laws that prevent water sales to Texas or require that any such agreements get legislative pre-approval.The high court's action could have major implications for North Texas water planners, who might have to give up on tapping Oklahoma as a resource.For the justices, the question is whether the case could cause national ripples.The district says the outcome has repercussions for more than 30 interstate water compacts nationwide. Oklahoma officials counter that this is a narrow dispute and that the water district only recently tried to amplify its significance.The Red River Compact assures each state "equitable apportionment of water" from the Red River and its tributaries. Congressional approval in 1980 gave the pact the force of federal law.The district had filed several permits, including one seeking 310,000 acre-feet of water from the Kiamichi River, far less than Texas' allotment under the compact, according to legal briefs. (An acre-foot is the volume of one acre of surface area to a depth of one foot -- about 325,000 gallons.) The district says Oklahoma lets millions of gallons of water run unused to the Gulf of Mexico.The water district says the compact and the Constitution's Commerce Clause should prevent Oklahoma from creating a permitting scheme that blocks Texans from getting their rightful share of water.But Oklahoma officials say they're within their authority. Last year, the Denver-based 10th U.S. Circuit Court of Appeals said Oklahoma has "wide berth to protect its compacted water against out-of-state transfer and use."The water district told the Supreme Court the appellate ruling allows "economic protectionism that will encourage retaliation" and "is fomenting significant tension between Texas and Oklahoma."The district serves about 1.6 million residents, including those in Fort Worth, Arlington and Mansfield, and expects its water needs to exceed supply by more than 400,000 acre-feet per year by 2060 as the area's population doubles.Last summer's drought, during Texas' driest year on record, underscored the danger of running short of water.The district's long-range plan includes a $1.9 billion pipeline in partnership with Dallas Water Utilities to bring water from three East Texas reservoirs.It seems that every time there was talk of settling the dispute with Oklahoma, too much of a gulf remained. Some Oklahoma legislators remain fiercely opposed to selling this precious commodity to other states.Legally, the problem seems to be language in the compact, which says it won't interfere with a state's right to control water within its borders as long as the state's exercise of its rights is consistent with its obligations under the compact.Sounds impossibly circuitous. Let's hope the Supreme Court can straighten it out and help the two sides see their way to a neighborly resolution.