Santa Fe County commissioners are expected to vote next month on a deal to create a regional water utility with four area pueblos, a project that would end more than half a century of divisive litigation over water rights in the Pojoaque Valley.

If the five-member commission approves an agreement to establish a governing board for the regional water system, the utility would divert flows from the Rio Grande at San Ildefonso Pueblo and send the water to county residents from Española to Santa Fe. And it would take an act of Congress to dissolve the system, the key part of a settlement in the nation’s longest-running federal lawsuit.

The Aamodt case, named for the first listed defendant — one of hundreds — was filed in 1966 by the New Mexico state engineer to determine water rights in the Pojoaque Basin river system that feeds into the Rio Grande, particularly in times of shortage. The contentious issue involves four pueblos in the area — Nambe, Tesuque, San Ildefonso and Pojoaque — as well as thousands of other residents tapping into private wells and using irrigation water.