The Ash Meadows refuge, for example, was slated to be the Calvada Lakes housing development — including more than 30,000 homes, golf courses and strip malls — when the Nature Conservancy bought it in 1984 and donated it to the federal government. Conservationists and refuge employees have been working to restore the landscape ever since.

There are persistent threats along the Amargosa, despite its protections. Work crews have removed miles of invasive tamarisk trees, for instance, because they take up and transpire so much of the river’s water. But the federal and private protections are useless against the biggest threat of all: the pumping of groundwater from the giant underground aquifer that feeds the Amargosa, which eventually may throttle the river and the delicate ecosystems it supports.

Much of the regional groundwater system that feeds these protected features comes from the flanks of Yucca Mountain, some 70 miles or so to the north. The Trump administration and Congress are working to restart moribund efforts to bury nuclear waste in the repository there.

While there is concern that someday — centuries or millenniums in the future — radioactive waste could contaminate the water in the Amargosa watershed, the more immediate threat is the need to pump enough groundwater to support the huge repository infrastructure.

“That would require thousands of acre-feet of water per year for up to a century,” said Robert J. Halstead, executive director of Nevada’s Agency for Nuclear Development, which opposes a Yucca Mountain repository. “That would clearly threaten the sustainability of the groundwater resource in Amargosa Valley.”