TUCSON, Ariz.— The Center for Biological Diversity filed a formal notice today of its intent to sue the U.S. Fish and Wildlife Service for failing to protect the imperiled least chub under the Endangered Species Act.

This small fish was once widely distributed in rivers, springs, marshes and ponds in Utah’s Bonneville Basin. Significant habitat loss and alteration, as well as competition and predation from non-native species, have driven this fish to the brink of extinction.

Following a 2021 petition from the Center seeking protection for the fish, the Service had until this September to make a final listing decision but missed this deadline.

Only seven wild populations of least chub survive. In addition, there are roughly a dozen introduced populations, which provide some assurances that if wild populations are lost, they can be replaced. However, in most cases, the longterm survival of these populations is uncertain and the sites where they occur are man-made or semi-natural.

More than half of the remaining wild populations are jeopardized by proposed groundwater pumping to support human population growth in Cedar City, Utah. The proposed Pine Valley Water Supply Project would pump billions of gallons of groundwater from Utah’s West Desert, threatening the springs the chub depends on.

“The least chub is in the crosshairs of the Pine Valley Water Supply Project," said Krista Kemppinen, Ph.D., a senior scientist at the Center. “If this desperately imperiled fish doesn’t get federal protections, the repercussions could be catastrophic.”

Despite the efforts by Utah to protect the least chub, the majority of wild populations continue to decline or are in a precarious state. Restoring populations is important, and the wild places where least chub continue to survive need to be protected.

“Endangered Species Act protection would ensure the Pine Valley water grab doesn’t jeopardize the survival of this tiny native Utah fish,” said Kemppinen.

Background

The least chub is a gold-colored minnow, typically less than 2.5 inches long, that has evolved to survive in the extreme spring habitats of the Bonneville Basin. First described in 1872, it is the only species in its genus, Iotichthys.

The least chub has been of conservation concern for decades. The Center for Biological Diversity petitioned for its listing under the Endangered Species Act in 2007. In response, the Service found that listing was warranted but failed to provide any protection.

In 2014 the Service reversed this finding, in part because of the implementation of additional conservation measures led by the Utah Division of Wildlife Resources.

In 2021 the Center again petitioned for protection. The Service had until September 2022 to make a final listing decision, but has yet to do so.