A controversial plan to replumb the California Delta — decades in the making — would funnel water from new intakes north of the delta as well as existing south Delta pumps, sending hundreds of thousands more acre-feet of water south instead of allowing it to flow out to the ocean. 

But the state’s environmental review has raised serious concerns that the tunnel project could harm endangered salmon and other species. And, if eventually approved, it would take decades to complete and cost billions of dollars.

In the meantime, California’s existing networks of pipes, aqueducts and canals lose precious supplies to leaks and evaporation. Some strategies have emerged to reduce these losses, including lining canals — which can also impede groundwater recharge — or covering them with solar panels. 

In cities and towns, water suppliers lose roughly 316,000 acre-feet of water every year through leaks in their vast mazes of pipes. The state set new standards requiring water providers to meet loss targets starting in 2028, which could save about 88,000 acre-feet a year.