The US Environmental Protection Agency (EPA) has issued the “largest single block of financing ever” for a wastewater treatment project.

The $1.6 billion (£1bn) funding will be used to upgrade the Sacramento Regional Wastewater Treatment Plant.

The EchoWater Project will bring the plant to “advanced treatment levels”, removing nearly 95% of ammonia from wastewater discharges, the EPA said.

Jared Blumenfeld, EPA’s Regional Administrator for the Pacific Southwest said: “California’s economic security depends on a healthy Bay Delta, the largest and most important estuary on the West Coast. EPA’s Clean Water Act State Revolving Funds are a key investment in clean water infrastructure to protect this precious resource.”

The Bay Delta is the hub of California’s water distribution system, supplying drinking water to 25 million people and irrigation water to four million acres of farmland.