LAS VEGAS— The Center for Biological Diversity launched a lawsuit today to block a proposed ski-resort expansion in southern Nevada that could drive the endangered Mount Charleston blue butterfly to extinction.

Today’s notice of intent to sue the U.S. Fish and Wildlife Service and U.S. Forest Service notes that the species is one of the most imperiled butterflies in North America. It’s native to the Spring Mountains above Las Vegas, and fewer than 100 individuals have been observed during surveys in the past five years.

The proposed ski-resort expansion would include new lift-assisted downhill mountain bike trails and a “mountain coaster.” These developments would open the area to summertime operations and thousands of visitors when the butterfly is active and most vulnerable. Despite these severe threats to the species, the Service approved the ski resort’s expansion.

“The beautiful Mount Charleston blue butterfly is teetering on the brink of extinction and a downhill sports amusement park is the last thing it needs,” said Patrick Donnelly, Nevada state director at the Center. “Previous recreational developments are exactly what made this butterfly endangered to begin with, so we’re intervening to prevent the government from dooming this species.”

The Humboldt-Toiyabe National Forest has aggressively pursued massive recreational developments in Lee Canyon, where the butterfly’s critical habitat is located. Those have included new picnic areas, campgrounds and other facilities that destroyed the butterfly’s habitat.

Today’s notice argues that the Service improperly analyzed the effects of the proposed developments, and that such impacts would adversely modify the protected critical habitat of the butterfly.

“The Endangered Species Act is the most successful conservation law in the world at preventing extinction, but sometimes we need to intervene to ensure that the government follows the law,” said Donnelly. “We’re in the middle of an extinction crisis, and we can’t afford to lose this unique and incredibly imperiled butterfly.”