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Crisis is brewing on the Colorado River, the result of decades of water use exceeding the river’s water supply, leaving some communities and ecosystems vulnerable—including the Grand Canyon. Climate change is making things worse, shrinking the river. NASA recently released documenting the decline of water stored in Lake Mead, a visual reminder that water users have drained nearly all their reserves and have no choice but to reduce demands. It’s not yet clear whether the seven Colorado River basin states and water users will reach collaborative agreements for voluntary and compensated reductions, whether federal leaders will have to make the hard choices, or whether courts will be the ultimate arbiters deciding who gets to use the water that’s left. It is clear the impact will be a significant reduction in water use, because water to supply all historic uses does not exist.

The Colorado River isn’t just a plumbing system for municipalities and agricultural economies, it’s an ecosystem, a living river home to myriad species. Before the reservoirs started to dry up, the clearest indication that supply and demand were out of balance was the elimination of the Colorado River Delta ecosystem, 1.5 million acres of wetlands where the river is supposed to meet the Gulf of California. That story is now a half century old, and Raise the River, a binational coalition of NGOs, has partnered with the United States and Mexican federal governments to restore a small fragment of that ecosystem to improve outcomes for birds and other wildlife.

This summer we learned that another Colorado River ecosystem is in trouble. The Grand Canyon sits between the two largest Colorado River reservoirs (in fact, the two largest in the country), uniquely exposed to the water supply crisis. The Grand Canyon may be one of the most iconic of the United States national parks, but it too is vulnerable to the brewing crisis.

The Colorado River within the Grand Canyon is managed under the 1992 Grand Canyon Protection Act. The U.S. Bureau of Reclamation and National Park Service, working with partner and stakeholder agencies, have collaborated for decades. Results of this collaboration include improved sediment flows that help maintain sandy beaches used by plants and animals that dwell in the floodplain, as well as by people traveling the canyon by boat. Results also include creation of in-river conditions conducive to maintaining the largest remaining population of Humpback Chub, a fish endemic to the whitewater reaches of deep canyons in the Colorado River Basin. In 1967 the Humpback Chub was listed as an endangered species, and in 2021 it was downlisted to threatened status, indicative of the remarkable efforts to help the species recover.

Yet the Humpback Chub may be in trouble again, vulnerable to predators including smallmouth bass and green sunfish. Water flowing from the shrinking Lake Powell into the Grand Canyon is getting warmer as the reservoir’s water surface drops closer to the turbine intakes on the face of the Glen Canyon Dam. Until recently the water flowing through those intakes, buried deep below the reservoir’s surface, was cold enough to keep predator fish away from passage into the Grand Canyon. In June 2022 research teams first reported detections of the predator fish downstream from Glen Canyon Dam.

If you have read this far and are asking yourself why you should be concerned about an endangered fish in the Grand Canyon while water supply challenges threaten drinking water and agricultural production at an unprecedented scale, consider this: as the water surface at Lake Powell continues to drop, there’s a mounting risk that it gets too low for any water to pass through the turbine intakes. Several bypass tubes sit below the turbine intakes, but Reclamation has expressed uncertainty about their ability to pass Colorado River water downstream on an extended basis. Left unchecked, the crisis brewing on the Colorado River won’t just threaten the Humpback Chub, it will threaten every living thing in the Grand Canyon. That includes not only fish, but also a diversity of wildlife including California Condors, Southwestern Willow Flycatchers, bald eagles, and herons, none of which will survive in the Grand Canyon if the river disappears. Already, Colorado River Basin States and Reclamation have agreed to emergency provisions to raise Lake Powell’s elevation through emergency releases from upstream reservoirs and reduced releases from the Glen Canyon Dam, but these measures are temporary and do nothing to balance supply and demand on the Colorado River.

Consider this: if the Colorado River disappears in the Grand Canyon, there won’t be any float trips through those hallowed red rock walls.

Consider this: if the Colorado River disappears in the Grand Canyon, there won’t be a Colorado River flowing into Lake Mead, and soon there won’t be a river flowing downstream from Hoover Dam either. Then the crisis is “day zero” with no Colorado River supply downstream in Arizona, California and Mexico, threatening every water user regardless of the seniority of their water right, the economic value of their water use, or their willingness to pay for water.

How we adapt to climate change in the Colorado River Basin is of enormous consequence to everyone and everything that depends on the river:

In the near term, Reclamation and the National Park Service should develop strategies to protect the incredible progress of the Humpback Chub, relying on physical removal of predator fish, and develop longer-term plans for mechanical strategies such as an engineered temperature control device. While the volume of water to be released from the Glen Canyon Dam cannot be modified for fish, and this year’s crisis situation at the Glen Canyon Dam precludes the flexibility to modify the timing of water releases (the hydrograph), the agencies have an opportunity to explore how 2023 operations could help limit predator fish migration into the territory of the Humpback Chub.

In the near term, states and water users should find ways to reduce water use that minimizes harm to vulnerable communities and ecosystems, and develop longer-term strategies that increase operational flexibility to respond to changing conditions in consideration of the full range of values supported by the Colorado River. There is also ample opportunity to use resources provided in the 2021 Bipartisan Infrastructure Law to increase system resilience, including improvements to reduce consumptive uses of water like irrigation infrastructure improvements that help farmers and ranchers and investments in urban conservation and reuse, and investments in native habitat.

Consider this: we have no choice at the moment but to adapt to the reduced water supply in the Colorado River Basin, as climate change impacts are here for the foreseeable future. But we do have an opportunity to limit how much climate changes in the future, and that requires all of us to insist that our elected leaders not just provide the resources to adapt to this terrible crisis on the Colorado River, but to enact comprehensive policy approaches to reduce carbon emissions and begin the hard work of climate change mitigation.