Now, researchers from the University of California are planning to cover the state’s canals with solar panels.
Spanning 6400 km, the state’s canal system is one of the world’s largest. But around 2% of the water it carries evaporates as it travels southwards.
Covering all canals could mean an annual saving of 247 billion litres of water, significantly relieving the strain on the groundwater system.
The move would also allow green electricity to be generated more efficiently: the panels are cooled by the water below.
Agriculturally useful land will be preserved, while shading the canals limits the growth of aquatic weeds.
The panels themselves could be cleaned like this.