In the closely watched and highly managed headwaters of the Muddy River, a tiny endangered fish continues to make giant strides.
A population survey conducted earlier this month turned up 1,727 Moapa dace, 546 more than researchers counted one year ago in the Warm Springs area about 60 miles north of Las Vegas.
That marks the highest total in more than a decade for the finger-length fish with the black spot on its tail.
The Moapa dace only lives in a few miles of warm, spring-fed streams that flow into an oasis of palm trees a few miles west of the town of Moapa.
The fish has been under federal protection since 1967, and it is expected to remain that way until at least 75 percent of its historical habitat has been restored and its population holds steady at 6,000 adult fish.
Extensive work has been done in recent years to remove non-native predator fish and rebuild natural stream channels that were diverted decades ago to support ranches and resorts in the area.
The U.S. Fish and Wildlife Service tallies Moapa dace each February and August with the help of the Southern Nevada Water Authority and the Nevada Department of Wildlife.
This year’s February count showed 1,226 fish, nearly double the 654 found in February 2012. The total in August 2012 was 1,181.
The dace’s entire habitat is confined to the 116-acre Moapa Valley National Wildlife Refuge, some adjacent private land and the Warm Springs Natural Area, a 1,218-acre tract the water authority bought for $69 million in 2007.
The wholesale water supplier for the Las Vegas Valley agreed to help protect the dace under a 2006 federal agreement that cleared the authority to pump groundwater at nearby Coyote Springs.
Environmental groups warn that large-scale groundwater pumping by the authority could dry out the Warm Springs area and finish off the Moapa dace.
The Center for Biological Diversity has sued the U.S. Fish and Wildlife Service over that very issue.
Contact reporter Henry Brean at email@example.com or 702-383-0350.