The overall value of real estate in San Diego County fell $568 million, or 0.14 percent, over the last year, according to a release from Assessor/Recorder/County Clerk Ernie Dronenburg.

The total value of properties assessed in the county stands at $395.1 billion, including $15.1 billion in tax-exempt property. This should generate about $3.8 billion in property taxes over the course of the year, assuming a base rate of 1 percent (though the effective rate paid by homeowners is closer to 1.25 percent after considering various bond measures).

“At least three major elements influenced the roll value for 2012,” Dronenburg said, citing continued weakness in the residential housing market, over 100,000 parcels being reassessed due to their market value being lower than assessed value, and the government purchase of the toll road section State Route 125, which alone knocked $300 million off the rolls.

Partially offsetting the losses, existing owners of undervalued parcels saw their tax bills increase by 2 percent, the maximum allowed under the state’s Proposition 13 law, which increased assessed values by $4.8 billion.

Of the county’s 18 cities, six lost value, with Chula Vista suffering the worst, losing 0.71 percent in value. The other 12 saw net gains, with Solana Beach faring best, experiencing a 4.88 percent gain in value. San Diego values were down about a quarter percent.