The 20-plus-year drought in the American West hit a new extreme this week as the US government declared a water shortage on the Colorado River for the first time in history.
The flow of the river, which shaped the Grand Canyon and cuts through seven western states, has fallen by 20 percent over the past century. It feeds the nation’s largest human-made reservoir, Lake Mead, which has also sunk to a record low.
The announcement of the shortage isn’t just symbolic. It also triggers mandatory water consumption cuts, which mostly impact Arizona, that take effect early next year. Some 40 million people rely on the river for water, contributing to its decline — to say nothing of the nearly 5.5 million acres of farmland that it irrigates.
What those figures miss are the countless plants and animals that also depend on water to survive in the harsh terrain of the western US. The megadrought is threatening wildlife, and state agencies are pouring in resources to keep important species alive — in some cases, by flying water in helicopters to remote, artificial watering holes where bears, sheep, and other thirsty animals seek relief.
These measures are quickly becoming the new normal, and they aren’t cheap. Flying a helicopter that air-drops hundreds of gallons of water, for example, can cost as much as $1,800 an hour, according to a biologist with the Arizona Game and Fish Department.
Scientists involved in wildlife conservation are concerned that as climate change makes droughts more frequent and severe, they’ll have to work harder to conserve plants and animals. And as more areas are forced to ration the scarce resource of water, they have to answer a difficult question: What do humans owe animals that are perishing from a problem of our own making?
How drought hurts animals
Wild animals can die of dehydration, but many of the major impacts of drought are far less obvious.
As the water level in lakes or streams falls, for example, it can heat up, causing the metabolism of cold-water fish to increase, according to Blair Wolf, a biology professor at the University of New Mexico. To sustain a faster metabolism, fish need more oxygen, yet warm water tends to hold less oxygen, he said. “The fish basically have a higher metabolism and there’s less oxygen available for them to breathe,” Wolf said.
What’s more, warmer water in the Colorado River basin tends to favor invasive species like smallmouth bass, research has found. “In the absence of effective management interventions, future warming is likely to disproportionately benefit nonnative species to the detriment of native species,” authors of a recent study wrote.
Drought also affects birds’ ability to tolerate extreme heat, according to Steven Beissinger, an ecologist at the University of California, Berkeley. Birds perspire through their mouth and skin to stay cool on hot days, which requires water. Plus, many species get all of their water from the food they eat. “So if it’s hotter and drier, they will need to eat more food,” Beissinger said. “This requires more energy or effort to obtain more food, which increases water needs further.”
At the same time, drought — and especially drought combined with rising temperatures — can make it harder for baby birds to survive and lead to population declines in at least some species, in part by making it tougher to find food, Wolf’s research has found. Water is incredibly important to desert plants, Wolf said, which feed rodents and other animals that birds eat.
“We found a rapid decline in burrowing owl population size strongly linked to extreme drought conditions,” he and his co-author wrote in a 2016 study about a population of owls in the Southwest that fell by more than 98 percent in 16 years.
Vegetation shortages can even make it harder for bucks to grow full-size antlers, which they use to compete with each other for mates and territory, according to the Utah Division of Wildlife Resources.
Not every species suffers when water levels fall. Some native fish, for example, actually seem to benefit from rising water temperatures in parts of the Colorado River basin, said Charles Yackulic, a researcher at the United States Geological Survey.
When reservoirs like Lake Mead are full, the water flowing out of dams tends to be cold and therefore uninhabitable for certain fish, including the humpback chub, an endangered species that prefers warmer waters. When the reservoirs shrink and release warmer water, certain downstream species may benefit: The humpback chub is doing so well these days that the Fish and Wildlife Service proposed downlisting the species last year from endangered to threatened.
But even those benefits likely have a limit, Yackulic says. Humpback chub can only tolerate warming water up to a point, and other parts of the river — where dams haven’t historically cooled the water as much — could soon become intolerably hot for native species, Yackulic said.
It’s getting harder and harder to keep animals alive
The US is the second-largest emitter of greenhouse gases, but it also has some of the world’s strongest environmental protections and institutions. They’re helping offset some of climate change’s worst symptoms, including severe drought.
A handful of states resort to dumping water in outdoor tanks where animals can reach them, creating a liquid lifeline that wild animals depend on. Last year, the Arizona Game and Fish Department (AGFD) hauled a record 2.4 million gallons of water to these catchments, and this year the state’s on track to haul 3 million gallons, according to Larisa Harding, the AGFD small game program manager. There are roughly 3,000 catchments in the state that hold anywhere from 2,500 to 10,000 gallons of water each, Cronkite News’s Nick Serpa reported in 2018.
“When we don’t get rain, we can make up that difference at least enough to keep those animals persisting,” Harding said. While it may sound far-out to build a whole separate network of water infrastructure for animals, the catchments are essential “if we want wildlife on the landscape when we have these extreme conditions,” Harding said. Providing water also means animals won’t have to walk far in pursuit of a drink, which can lower the likelihood of road collisions, she said.
Wildlife agencies have a number of other tools at their disposal, some of which require more work than others. Earlier this year, the California Department of Fish and Wildlife trucked millions of juvenile salmon from rivers that were drying up in the Central Valley to the Pacific Ocean. Some states have also limited hunting permits owing to “reduced productivity of critical wildlife ranges.”
There are also a number of other government-run conservation programs across the Colorado River basin. The Lower Colorado River Multi-Species Conservation Program, for example, was set up to offset damages to wildlife — especially animals listed under the Endangered Species Act — caused by all kinds of river operations, including diverting water and generating hydroelectric power, according to John Swett, who manages the program.
But experts say many of these projects are only temporary solutions, and it’s not clear to what extent they help. Catchments, for example, have a pretty isolated effect and aren’t typically used by migratory birds, Wolf said. Plus, flying helicopters, hauling salmon, and limiting permits are expensive and already hard to sustain. A lot of effort is going into just keeping populations stable.
So what happens as climate change makes these problems worse?
“I talk to a lot of management agency folks, and that is a concern: How much longer can we maintain efforts as water becomes just rare in general?” Yackulic said. “Sometimes it’s about the financial costs, but sometimes it’s just about the water itself.”
What humans owe animals
Government agencies in the US are required by law to protect endangered and threatened species, and we conserve some animals because they provide valuable services, like pollination. But aside from that, what do humans owe animals that are in decline thanks to problems — like severe drought — that people helped create?
“You would hope humans would have some sense of responsibility,” Wolf said. But “humans are selfish,” he added. “Allocating water for a minnow or a trout or a fish or a frog is hard to justify in people’s minds.”
Other scientists Vox spoke to were also at a loss for how to balance rising human demands with the needs of wildlife in a rapidly warming world, though they all felt a personal sense of responsibility. “I try to be a good steward of the land,” Harding said. “I try to look for the best ways to promote wildlife health and habitat health.”
Wolf, meanwhile, finds fulfillment in educating the next generation “on what’s happening, why it’s happening, and what can be done about it,” he said.
Of course, it’s that last part — what we can do — that really matters. And ultimately, it will have to be much more than airlifting water and, perhaps, require us to put the needs of ecosystems and the animals that inhabit them above our own.