LAS VEGAS (AP) - Nevada's top water regulator has joined the Southern Nevada Water Authority in appealing a court ruling that dealt a blow to the authority's plans to tap groundwater in Lincoln County.

The state engineer's office filed its notice of appeal with the Nevada Supreme Court on Friday.

At issue is District Judge Norman Robison's Oct. 15 decision to strike down a July 2008 order from State Engineer Tracy Taylor that allowed the pumping of more than 6 billion gallons of groundwater a year from Cave, Delamar and Dry Lake valleys.

It represented the first phase of the authority's proposal to tap groundwater from rural Nevada and pipe it south to supplement Las Vegas amid drought along the Colorado River.

The water authority board on Thursday voted to appeal Robison's decision.