Antioch received a blow from the Contra Costa County Assessor's Office this week: A 21.7 percent reduction in property tax revenue that will put the struggling city another $3.25 million in the red.

The city had budgeted for a 4 percent year-over-year drop in property tax revenues, with a 10 percent or 12 percent hit considered the worst-case scenario.

This brings Antioch's operating deficit to about $6.6 million. That's after the $5 million in cuts the City Council has already approved.

City Manager Jim Jakel said he has confirmed the numbers with county Assessor Gus Kramer.

"It means we can't maintain operating in the current manner," he said. "We're going to have to make significant operational changes."

The city's rainy day reserve account only has $3.8 million in it, meaning that even dipping into that wouldn't solve the shortfall, Jakel said.

Antioch is now projecting revenues of only $35 million for the 2009-10 fiscal year— $11 million less than a couple years ago.