California Solar Canals Save 70% Water While Generating Power

Water is vanishing from California's canals before it even reaches farms and homes, but a simple solution is proving it doesn't have to.

Solar panels installed above two irrigation canals south of Modesto reduced water evaporation by up to 70 percent over a full growing season. The same shaded canals also cut weed and algae growth by 85 percent, saving operators countless hours of maintenance work.

Project Nexus, funded with $20 million in state money, built steel-framed solar canopies over canal sections totaling about one and a half football fields. The installations now generate 1.6 megawatts of power, enough to serve hundreds of homes.

California operates roughly 4,000 miles of open irrigation canals carrying water across the state. Researchers at UC Merced calculated that covering all of them with solar panels could save 63 billion gallons of water each year. That's enough to serve 2 million people or irrigate 50,000 acres of farmland.

The same coverage would generate 13 gigawatts of electricity, roughly half the new solar California needs to meet its 2030 renewable energy targets. No one expects the entire network to get covered, but even a fraction would make a meaningful difference.

The technology costs more to build than traditional ground-mounted solar farms. That's why the water savings and reduced maintenance matter so much to the economics.

Josh Weimer, director of external affairs for Turlock Irrigation District, says a new report expected in coming months will be "critical" to deciding whether they invest further. Canal operators spend significant resources fighting aquatic weeds throughout the irrigation season, so an 85 percent reduction changes the cost calculation.

The Ripple Effect

The concept is already spreading. Gujarat, India completed two solar canal projects over a decade ago. In 2024, the Gila River Indian Community built one along Interstate 10 south of Phoenix, producing 25 percent more power than projected.

Water temperatures in the Arizona canal dropped a full degree as it traveled through two-thirds of a mile of shaded canal, with zero algae growth recorded. David DeJong, the irrigation project director, called the potential impact on the American West a "paradigm shift."

The California Department of Water Resources is tracking Project Nexus results closely as it evaluates solar canals for the State Water Project, which serves 27 million people. Andrew Schwarz, the agency's climate action manager, says the data will be "essential" to understanding real-world performance.

Roger Bales, professor emeritus at UC Merced, estimates California could generate up to one gigawatt of solar power from canals within the next decade. "We have to get to a hundred miles, and then it might take off," he said.

The smartest near-term locations are canals sitting next to water-pumping stations, highway EV charging sites, or anywhere local power lines can absorb the electricity without requiring new transmission infrastructure.

One and a half football fields of solar canal won't answer every question, but it's proving that saving water and generating clean energy in the same space is more than just a good idea on paper.