In Hickman, California, about 100 miles east of the Bay Area, a stretch of irrigation canal now runs beneath a roof of solar panels. KPIX visited on a day the reporter puts at 100 degrees, which is the entire point: the Turlock Irrigation District loses a large volume of water to evaporation in exactly that heat. Josh Weimer, the district's director of external affairs, tells the station there are more than 700 panels at the site producing about 800 kilowatts, and that the main canal beneath them is 110 feet wide. The district runs 250 miles of canals serving 145,000 acres of almonds and corn. Statewide, the station reports, canals lose enough water to evaporation to supply two million people. In 2023, the station notes, this site was still just an idea on paper.
The installation is one half of a research project that has been watched closely since a 2021 University of California, Merced study suggested the idea might scale. The New York Times reported in June that the effort, called Project Nexus, was built with $20 million in state funding, and that the original study modeled covering all 4,000 miles of California's major open canals, which it projected could generate around 13 gigawatts and save 63 billion gallons of water a year. The Times also reported that the two Turlock installations together generate 1.6 megawatts, that preliminary sensor readings showed evaporation down by up to 70 percent, and aquatic weeds and algae down by up to 85 percent. Two things from that same report are worth holding alongside the enthusiasm: the study's lead author considers covering all 4,000 miles unrealistic, and building over a canal costs more than building on open ground. That cost gap is the number that decides whether any of this spreads.
KPIX puts the practical question to Dr. Brandi McKuin of UC Merced, who is part of the research team, and her answer is measured. She says the panels are reducing evaporation and reducing aquatic weed growth, but that the jury is still out on whether the total cost justifies expanding the project. She adds that open questions remain about how much water is actually saved, how much weed growth is prevented, and where the approach makes sense at all. Weimer frames the district's involvement as consistent with its history, describing Turlock as the first irrigation district in California with an innovative culture at its core, and notes that until the UC Merced paper there were plenty of reasons not to cover a canal. The station describes two test sites built to different geometries: the wide span shown on camera, and a narrower span near Keys Road. The Times reported that the district is 139 years old and distributes electricity to 240,000 people, and that a comparable canal project built by the Gila River Indian Community in Arizona in 2024 ended up generating 1.5 megawatts, around 25 percent above its estimate, with the cooling effect of the water beneath the panels offered as a possible explanation.
Bottom line: The number to watch here is not 800 kilowatts, it is the 70 percent evaporation figure, because water is the thing California actually fights over. Solar canals are never going to beat a desert solar farm on cost per megawatt hour and probably never will. They win only if a district can put a hard value on the water it keeps, the land it does not have to buy, and the weeds it does not have to clear. If the forthcoming UC Merced economics report lands well, expect other districts to move quickly. If it does not, this stays an unusually well documented demonstration project.
Commentary on a third-party video. Figures and claims are as presented in the source and have not been independently verified. Spotted an error? Tell us and we will correct it.