The Moapa Valley National Wildlife Refuge was established on September 10, 1979, to secure habitat for the endangered¬†Moapa dace, a small fish endemic to the headwaters of the Muddy River system. Dace populations were in peril due to habitat destruction and modification. Competition with introduced species such as mosquitofish, shortfin molly, and tilapia also contributed to the dace’s decline. However, as more and more habitat is restored and non-native species are removed, the fish has begun to rebound. Recent population surveys show an increase in numbers from recent years. As of February 2020, there were 1340 dace in the Muddy River system. Biologists say that there needs to be a stable population of at least 6000 to ensure the security of the species.

The refuge is located on 116 acres in northeastern Clark County and is approximately 60 miles north of Las Vegas, Nevada. Dace habitat on the refuge consists of stream channels supported by six thermal springs, three of which are within refuge boundaries.

Due to its small size, fragile habitats, and on-going restoration work, the wildlife refuge is only open Friday, Saturday and Sunday, sunrise to sunset, from September through May. The wildlife refuge is closed during June, July, and August.