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The Colorado River is flowing again in its delta. This is a big deal for a river that has not flowed through its delta in most years since the 1960s, resulting in an ecosystem that is severely desiccated and devastated.

Thanks to commitments from the United States and Mexico in the Colorado River binational agreement—Minute 323 –  35,000 acre-feet of water (11.4 billion gallons) dedicated to create environmental benefits will be delivered to the river from May 1 to October 11. The expectation is that this will create and support habitat for birds like the Yellow-billed Cuckoo, Yuma Ridgway’s Rail, and Vermilion Flycatcher, and give life to the many plants and animals in this ribbon oasis of green in the midst of the Sonoran Desert.

The last time the two governments cooperated to put water for the environment into the Colorado River was in 2014, when they released a “pulse flow” of water from Morelos Dam (the furthest downstream dam on the Colorado River, located at the U.S. – Mexico border). For eight glorious weeks, the Colorado River was conjured back to life in its final 100 miles. Birds took notice (bird abundance increased 20% from the previous year, and species diversity increased 42%) and local communities celebrated with a spontaneous river fiesta that went on for weeks.

This time, the water will flow for more than five months. Thanks to lessons learned from scientists who studied the 2014 pulse flow, the water will be less likely to infiltrate into the ground, and more likely to fill the river channel providing environmental benefits all the way down to the Gulf of California. System operators are using Mexico’s canal system to bypass Morelos Dam and the driest parts of the channel, delivering the water into the river some 45 river-miles downstream. There it will fill the river where the channel is already wet, maximizing water use efficiency. The scientists’ design optimizes the location and timing of flow to support the hundreds of species of birds that use the delta, and the floodplain habitats they rely on.

̽����ѡ and its partners in —the non-governmental organization (NGO) coalition working to restore the Colorado River Delta—are excited to see this sophisticated approach to environmental water delivery. Scientists will study the flow again this year in order to add to our understanding of how to best use the limited supply of water available for the environment.

The agreement that made these flows possible—Minute 323—lasts through 2026. The agreement also commits more than $30 million for water conservation infrastructure in the Mexicali Valley. The water savings will improve local resilience to global warming, increase the water supply stored in Lake Mead, make additional water available to water users in the United States, and create additional water supply for the environment (the coalition of NGOs will also contribute from a local water trust). Minute 323 also ensures that the United States and Mexico conserve Colorado River water and share in shortages when supplies are low. In the context of a drought on the Colorado River that has persisted since 2000, and the expectation of climate change exacerbating drought conditions, these provisions create water supply reliability for both people and nature.

This spring, water for the Colorado River Delta creates a renewed sense of hope. Over the next few months we have the opportunity to see what a small volume of water can do to revive the remnant ecosystem, to nurture its birds, and gift local communities with the return of their river. We can be reassured that, at least in parts of the delta, the Colorado River lives again. In an extraordinarily dry year, deliberate management of water to sustain the environment is the kind of management we will need throughout the Colorado River Basin to ensure that persistent drought and long term impacts of climate change do not lead to the end of river ecosystems in the arid West.