America's First Solar Panel-Covered Irrigation Canals Planned in California, Ari...

In 2015 the founders of "Solar AquaGrid" proposed water-saving solar panels to shade irrigation canals, but they "couldn't get anyone to commit," remembers the Associated Press.

But "fast forward eight years," and you'll find them "preparing to break ground on the first solar-covered canal project in the United States."

The idea is simple: install solar panels over canals in sunny, water-scarce regions where they reduce evaporation and make electricity. A study by the University of California, Merced gives a boost to the idea, estimating that 63 billion gallons of water could be saved by covering California's 4,000 miles of canals. Researchers believe that much installed solar would also generate a significant amount of electricity.

But that's an estimate — neither it, nor other potential benefits have been tested scientifically. That's about to change with Project Nexus in California's Central Valley...

They thought research from a reputable institution might do the trick, and [in 2021] got funding for UC Merced to study the impact of solar-covered-canals in California... Around the same time, the Turlock Irrigation District, an entity that also provides power, reached out to UC Merced. It was looking to build a solar project to comply with the state's increased goal of 100% renewable energy by 2045. But land was very expensive, so building atop existing infrastructure was appealing. Then there was the prospect that shade from panels might reduce weeds growing in the canals — a problem that costs this utility $1 million annually...

The state committed $20 million in public funds, turning the pilot into a three-party collaboration among the private, public and academic sectors. About 1.6 miles (2.6 kilometers) of canals between 20 and 110 feet wide will be covered with solar panels between five and 15 feet off the ground. The UC Merced team will study impacts ranging from evaporation to water quality, said Brandi McKuin, lead researcher on the study. "We need to get to the heart of those questions before we make any recommendations about how to do this more widely," she said.
"California isn't first with this technology," the article points out, since India "pioneered it on one of the largest irrigation projects in the world..." But soon even more U.S. canals may be getting solar panels.

Arizona's Gila River Indian Community "received funding from the Bipartisan Infrastructure Law to install solar on their canals in an effort to save water to ease stress on the Colorado River. And one of Arizona's largest water and power utilities, the Salt River Project, is studying the technology alongside Arizona State University. And a group of more than 100 climate advocacy groups, including the Center for Biological Diversity and Greenpeace, have now sent a letter to Interior Secretary Deb Haaland and Bureau Commissioner Camille Touton urging them "to accelerate the widespread deployment of solar photovoltaic energy systems" above the Bureau's canals and aqueducts. Covering all 8,000 miles of Bureau-owned canals and aqueducts could "generate over 25 gigawatts of renewable energy — enough to power nearly 20 million homes — and reduce water evaporation by tens of billions of gallons."