Seven years ago, a pulse of water on the Colorado River at the U.S.-Mexico border temporarily reconnected it to the Pacific Ocean. Scientists used the so-called 鈥減ulse flow鈥� to study what plant and animal life returned to the desiccated delta along with water.
Armed with that knowledge, scientists and conservation groups are trying a new and more targeted strategy to bring water back to the final 100 miles of the Colorado River this year.
It鈥檚 an attempt to reconnect portions of the river left dry from decades of overuse, and it鈥檚 happening in one of the driest years the basin has ever seen.
A paradoxical estuary
Just after sunrise in the Colorado River鈥檚 dry estuary in Mexico, during a mid-June heatwave, Tom谩s Rivas hunched over a line of tiny bits of wood and debris, left in a neat row from the receding tide. He used his fingers to comb through it.
He hoped to find jumping spiders, one of the smaller resident species of the river鈥檚 estuary.
Rivas is an ecologist with the Sonoran Institute, a conservation group. A century ago, the spot where he hunted for spiders would鈥檝e been covered by water. By definition, an estuary is a place where brackish ocean water meets and mixes with a freshwater river. It takes the two 鈥� ocean and river 鈥� to make the whole.
There鈥檚 no good substitute word for what the Colorado River delta is now. The Gulf of California鈥檚 tides still reach up into the Sonoran Desert. But there鈥檚 no river water. Dams along the Colorado River鈥檚 length in the U.S. and Mexico draw its water away to serve farms and cities throughout the region. Rather than emptying into the ocean, its water grows citrus in Arizona and greens up lawns in Los Angeles.
The delta鈥檚 exposed salt flats aren鈥檛 a wasteland. As Rivas explained, if you look close enough, you鈥檒l see the animals and plants able to make a home: jumping spiders, tiny turquoise fiddler crabs, hardy species of saltgrass.
鈥淭hese are harsh conditions here,鈥� Rivas said. That day, it reached 120 degrees.
One almost forgotten feature of the Colorado River delta is its tidal bore 鈥� a wave that formed as the incoming tide rushed against the freshwater river.
鈥淚n Spanish the people locally call it, 鈥�El Burro,鈥� for the tidal bore,鈥� Rivas said. It even had a sound, he said, of crashing, rumbling water. 鈥淧eople say, 鈥�Hay viene el burro鈥� which is like, 鈥楾he donkey's coming.鈥欌€�
Because the Colorado River is so overused, El Burro hasn鈥檛 charged in its delta in decades.
Rivas鈥� group, along with other Mexican and American environmental groups, are working to bring water back into this part of the estuary and study what happens. Some of the restoration work is funded by the Walton Family Foundation, which also supports 皇冠网址鈥檚 Colorado River coverage.
Additional water releases into the delta began May 1 and will extend to October, with peaking flows in early summer. The water volume won鈥檛 be enough to fully revive the tidal bore, but Rivas said it can help restore riverine habitat.
'A little bit of repair鈥�
This spring and summer, portions of the Colorado River delta flowed again. But unlike 2014鈥檚 pulse flow, where the dam at the U.S.-Mexico border sent a huge volume all at once, this year鈥檚 releases of water are targeted to restoration sites.
鈥淔or Mexico, living with a dead river has been, I'll say, sort of a wound,鈥� said Jennifer Pitt, director of the National Audubon Society鈥檚 Colorado River program. Pitt鈥檚 work also receives funding from the Walton Family Foundation.
鈥淭his is a little bit of repair,鈥� she said, pointing to an irrigation canal where water gushed back into the river鈥檚 channel. The water is diverted near the U.S.-Mexico border.
鈥淲e're using the irrigation canals to bypass the dry reach,鈥� Pitt said. 鈥淎nd drop the water into the river at the point where the scientists tell us it will do the most good.鈥�
The Colorado River is grabbing national headlines this summer as water shortages become more urgent. Hot and dry conditions are coming home to roost in its reservoirs, dropping the two biggest 鈥� Lakes Mead and Powell 鈥� to record lows. Even in a dry year like this one, Pitt said both the U.S. and Mexico have agreed to set aside water for the environment.
鈥淚f we don't figure out at this moment how to support the river itself and all of nature that it supports, I fear that we lose them permanently. So I think at this time it is more important than ever,鈥� she said.
That idea of carving out water supplies just for the river itself remains controversial. Some skeptical city leaders and farmers in Mexico have said any water spilling into the ocean is wasted, said Carlos de la Parra, a professor at El Colegio de la Frontera Norte, who鈥檚 acted as an adviser to the International Boundary Water Commission.
鈥淭here are voices out there that are saying, 鈥楽top this, you are wasting water,鈥欌€� he said. 鈥淚t really depends on the perspective you have.鈥�
The flows happening this year were part of an update to the 1944 treaty that the U.S. and Mexico use to govern their shares of the Colorado River. Over the last 21 years of ongoing hot and dry conditions, de la Parra said the two countries have transitioned from a relationship held at arm鈥檚 length to one of mutual respect. That led to a commitment from the U.S. to fund irrigation efficiency projects in Mexico, with some of the conserved water from those upgrades being set aside for environmental flows.
鈥淟ook around the world for another border that joins two countries that are so dissimilar and you're hard pressed to find it,鈥� he said. 鈥淲e're friends, we're partners. And so because we are so dissimilar, maybe we have the opportunity to become a model.鈥�
The pulse flow鈥檚 legacy
At Laguna Grande, one of the more mature restoration sites in the delta, groves of cottonwood and mesquite trees line the river channel. Dragonflies, endangered birds and even a few beavers have taken up residence. During this year鈥檚 peak flows, which lasted about 80 days starting May 1, enough water filled the channel to float a kayak. At a spot just downstream of the site, nearby residents jumped in to cool off.
鈥淭his is one percent of the water that's coming from the U.S. and it's building so much into the ecosystem,鈥� said Rocio Torres, the Sonoran Institute鈥檚 lead for Colorado River delta restoration. 鈥淔or me, and for our team, that means there's hope.鈥�
Torres said these targeted flows are less flashy, and harder to explain than the pulse flow. In 2014 it was easy and accurate to say that the river was fully connected to the ocean for weeks. This year it takes a bit more understanding of Mexican irrigation infrastructure and delta geography to fully grasp what鈥檚 happening.
But Torres said the flows happening this year wouldn鈥檛 have occurred without the pulse flow seven years ago. The event galvanized communities in the region, she said. It built a base of support from water officials in both countries who agreed to set aside a small amount of water to benefit the plants and animals deprived for so long.
鈥淚 think that's the way human beings, we learn,鈥� she said. 鈥淲e messed things up. We realized we shouldn't have done that,鈥� and bringing it back happens little by little.
This story is part of ongoing coverage of the Colorado River, produced by 皇冠网址, with support from the Walton Family Foundation.
