SACRAMENTO, Calif. (AP) — California will need to spend $650 million to clean up a heavily contaminated battery recycling plant in Southern California, but has less than half the money in hand and is behind its estimated schedule for removing dangerous lead dust affecting 100,000 nearby residents, the state auditor said Tuesday.

The Exide plant in Vernon recycled 11 million lead-acid batteries each year until it shut down in 2015. The state Department of Toxic Substances Control has been working since then to remove lead contamination from the surrounding area.

Auditors said the department will need another $390 million it currently doesn't have to complete the project and is “significantly behind schedule” and unlikely to meet its goal of cleaning up lead contamination from the 3,200 most contaminated properties by next July.

Department director Meredith Williams responded that her agency “has cleaned up more properties, more quickly than any other residential lead cleanup in the nation.” She argued that it could not anticipate some of the developments that have slowed its progress, like rain delays or properties where soil would have to be removed by hand or with specialized equipment.

She called it “the largest, most logistically complex residential cleanup project the state of California has ever undertaken.”

The department has yet to clean up 31 of the 50 sites that are frequented by children who are most at risk, including two schools, three parks and 26 childcare centers, auditors said.

Williams said it has cleaned up seven schools and 17 daycare centers and believes the contaminated soil is contained by grass or mulch at the remaining sites.

Auditors said the state so far lacks even a plan to clean up the remaining 4,600 properties near the plant. Department officials blamed a lack of funding.

Assemblyman Miguel Santiago, a Democrat who represents the area and sought the audit, called the department's progress “unacceptable” and called on officials to "fix their mistakes and create a realistic plan to clean up every single contaminated property.”

Lead dust, which can cause developmental disabilities, cancer and other long-term illnesses, contaminated the soil around thousands of homes where about 100,000 people live in Boyle Heights, east Los Angeles, Maywood, Huntington Park and Commerce.

The department is likely to drain its initial state funding before it can remove lead from 269 of the 3,200 most contaminated properties, auditors predicted. Auditors said Exide’s bankruptcy “leaves significant questions about the state’s ability to obtain reimbursement for the cleanup.”

They said state officials underestimated the total cost by failing to account for predictable costs including inflation. The department also paid $17 million more than it projected to clean 768 properties because it agreed to pay for cost overruns instead of requiring its largest cleanup contractor to pay any unexpected costs.

Williams said her department has finished more than 2,000 cleanups and recently stepped up its pace to decontaminate at a rate of 24 properties per week.