California canal solar project reduces evaporation and generates power | Making a Difference

Why this story matters: This article cuts through the sensationalism to provide a clear, constructive look at a project that is actually working. It’s a reminder that behind every great achievement is a group of people who refused to give up.

Quick summary: This story highlights recent developments related to climate action, showing how constructive action can lead to meaningful results.

Shade from solar panels installed above two California irrigation canals reduced water evaporation by up to 70 percent and cut aquatic weed and algae growth by up to 85 percent over a full irrigation season, according to data from Project Nexus, a state-funded pilot in the Central Valley.

Those aren’t the numbers the program set out to prove; the primary case was always about energy generation. But for a technology that costs more to build than ground-mounted solar, the water and maintenance results may be what make the economics work.

California’s canal network doubles as solar infrastructure

California operates roughly 4,000 miles of open irrigation canals, delivering water to farms and homes across the state. Project Nexus, funded with $20 million in state money, tested whether that network can also generate electricity.

The pilot, a collaboration between the University of California, Merced, the Turlock Irrigation District, and solar developer Solar AquaGrid, installed steel-framed solar canopies above two canals south of Modesto. One canal is roughly as wide as an alleyway; the other spans about the width of an eight-lane highway. Together they cover an area roughly equivalent to one and a half football fields and generate 1.6 megawatts of combined power.

The math behind scaling up

A 2021 UC Merced study modeled the effects of covering all 4,000 miles of California’s major open canals with solar panels. The projection: 13 gigawatts of generating capacity, roughly half the new solar California needs to meet its 2030 renewable targets, and 63 billion gallons of water saved each year, enough to serve 2 million people or irrigate 50,000 acres of farmland.

Lead researcher Brandi McKuin is direct about the ceiling. Canal shapes, conditions, and locations vary too widely, and the construction costs are higher than those for ground-mounted desert solar. “It’s probably unrealistic to assume that we’re going to cover all 4,000 miles of California’s canals,” she said. Even so, the modeling showed that covering a fraction of the network would produce output worth having.

Why the economics could justify the cost

For canal operators, the question isn’t whether solar canopies generate power. It’s whether the total value of power generation, conserved water, land savings, and reduced weed maintenance justifies the additional cost over conventional solar.

That math isn’t settled yet. A new UC Merced report expected in the coming months will be “critical” to whether the Turlock Irrigation District invests further, according to Josh Weimer, the district’s director of external affairs. The 85 percent reduction in aquatic weed and algae growth is not a minor operational footnote; canal operators spend considerable resources managing those weeds through the irrigation season.

The California Department of Water Resources is also tracking the results as it evaluates solar canals for portions of the State Water Project, which serves 27 million people. Data from Project Nexus will be “essential” to understanding real-world performance, said Andrew Schwarz, the agency’s climate action manager.

Early results in India and Arizona

California is not the first. Gujarat, in western India, completed two solar canal projects more than a decade ago. In 2024, the Gila River Indian Community built one along Interstate 10 south of Phoenix, Arizona.

The Gila River project is producing 1.5 megawatts, 25 percent more than projected, possibly because water cools the panels from below and raises their efficiency. Water temperature dropped a full degree Fahrenheit as it traveled through 3,500 feet (roughly two-thirds of a mile) of shaded canal, with no algae growth recorded. David DeJong, the irrigation project director, described the potential impact on the American West as a “paradigm shift.”

From pilot to the first 100 miles

Roger Bales, professor emeritus of civil and environmental engineering at UC Merced, estimates California’s canal network could generate up to one gigawatt of solar power within the next decade, provided the first 100 miles get built. “We have to get to a hundred miles, and then it might take off,” he said.

The near-term strategy, according to Solar AquaGrid chief executive Jordan Harris, is finding locations where canals sit adjacent to existing energy needs: water-pumping stations, EV charging sites along highways, or anywhere a local power line can absorb generation without requiring new transmission infrastructure.

McKuin said more research is needed before any broad commitment. “It’s still really early to say what the economic feasibility of this is,” she said. The data from one and a half football fields of solar canal won’t settle the question, but it’s the first real-world evidence that the three-part case for the technology holds up outside a simulation.

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