FLAGSTAFF, Ariz.— The Center for Biological Diversity urged the Federal Energy Regulatory Commission today to deny a preliminary permit application for a massive water-pumping project on the Little Colorado River, which provides water for one of the West’s most endangered fish.

It’s the third such Grand Canyon-area project proposed by a Phoenix-based firm in recent months.

The Big Canyon pumped storage project proposes large-scale groundwater pumping that could deplete Blue Springs, the Little Colorado River’s only source of year-round surface flows immediately upstream from Grand Canyon National Park. That part of the river harbors the largest remaining population of endangered humpback chub.

“This preposterous project threatens irreversible damage to the Little Colorado River and fast-tracks the extinction of humpback chub. We’re not going to let that happen,” said Taylor McKinnon, a senior campaigner at the Center. “The commission should reject this dangerous proposal immediately.”

The project would pump groundwater to fill and maintain a lower reservoir in Big Canyon, a tributary to the Little Colorado River, and three reservoirs on the adjacent canyon rim. It would pump water uphill to the rim when electricity prices are low to generate electricity and revenue from return flows when prices are higher.

Applicants for the Big Canyon project have proposed two other pump-storage projects in the same area, Little Colorado River and Salt Trail Canyon. Each would construct one dam on the Little Colorado River and reservoirs on the adjacent canyon rims.

The Big Canyon project’s groundwater pumping would deplete spring and Little Colorado River base flows and harm or destroy the chub’s entire critical habitat in the river. An earlier Center analysis showed that, by itself, the Salt Trail Canyon project would also destroy or harm the chub’s entire critical habitat in the river, and the Little Colorado River project would destroy or harm 87% of it.

Separate filings from the Interior Department and the Arizona Game and Fish Department about the nearby proposals also raised concerns about impacts on the chub. The agencies said the Little Colorado River is “a significantly important stream for the endangered humpback chub across the range of the species” and that the Salt Trail and Little Colorado projects would result in “a major decline and possible extirpation of the only remaining population of humpback chub in the lower Colorado River basin.”

Native American tribes including the Havasupai, Hopi, Hualapai and Navajo have opposed pumped storage in the area because of the harm the projects would inflict on sacred sites and cultural values. All three proposed projects would be located on Navajo Nation land.