Although many of the 492,000 taxable residential and commercial properties evaluated by the assessor's office saw their values rise or at least stay the same, 22 percent had reduced assessments, bringing the county's total taxable dollar value to $192.0 billion from $192.1 billion.
The assessed value of a property determines how much property tax the county will receive to fund safety net services for residents. The dip marks only the third year in at least five decades that the county assessment roll has fallen. The average annual growth in past years was 8 percent.
Not even the growth in Berkeley, Piedmont and Dublin -- the highest in the county -- tipped the scales enough to close the gap.
The slight decrease countywide was not enough to hurt the county's budget, though the outcome was still disappointing. The county was expecting a 1 percent increase. And 90 percent of the county's limited discretionary revenue depends on property tax dollars.
Revenue might have been higher overall in a better market, Alameda County Chief Deputy Assessor Brian Hitomi said. But banks are still being tight with credit and new construction is on hold.
The numbers, Hitomi said, are an indicator of "how thing are going" in the overall economy.
Judging by the conservative budgeting by cities, the overall economy still is precarious.
"We didn't want to anticipate growth and get burned by it," said David McPherson, revenue and tax administrator for the city of Oakland, which saw a 1.67 percent rise.
Emeryville, in contrast, came in 6.62 percent below last year, a decrease of about $277.6 million. The drop seemed like a reversal of fortunes for the city studded with big-box stores such as Home Depot, Ikea and Barnes & Noble. Emeryville had escaped declines in previous years while some of its neighbors scrambled to compensate.
The city's chief financial officer, Karan Reid, attributed this year's decline to several one-time but significant events for which Emeryville had braced itself. The dramatic write-down of the Watergate Towers office complex topped the list.
The city also suffered after the county cleared a backlog of applications from businesses requesting their property assessments be lowered.
Emeryville will be able to contain the impact of the decline. In fact, Reid said she had expected a much larger drop. Unlike many cities, property tax makes up a small portion of general fund revenue in Emeryville. Capital projects, business subsidies and low-income subsidies will feel a pinch because they are funded through property taxes.
Fremont also had braced itself for the inevitable blow from last year's closure of the NUMMI auto plant and sale of the land to Tesla Motors and Union Pacific. The city was told to expect a 40 percent plunge in the parcel's value.
The news that Pleasanton values declined by $204.7 million did not come as a shock to finance director Emily Wagner. She had budgeted for the foreclosure of the five-building Stoneridge Corporate Plaza next to Stoneridge Mall, as well as the Britannia Business Center II complex.
Both sold for less than their original value. Residential homes, however, saw a slight uptick. Pleasanton's forecasts were "pretty close," Wagner said. "We anticipated zero growth."
alameda county property assessments
City 2010-11 2011-12 Percent change
Alameda: $9,325,893,920 $9,452,764,771 1.36 percent
Albany: $1,923,568,649 $1,949,825,015 1.36 percent
Berkeley: $13,503,553,510 $13,898,473,845 2.92 percent
Dublin: $8,305,389,045 $8,482,846,995 2.14 percent
Emeryville: $4,190,790,315 $3,913,230,353 -6.62 percent
Fremont: $34,644,104,304 $34,122,490,940 -1.51 percent
Hayward: $15,052,324,745 $15,144,404,001 0.61 percent
Livermore: $13,242,040,030 $13,299,228,698 0.43 percent
Newark: $5,537,466,631 $5,572,210,275   0.63 percent
Oakland: $41,234,044,680 $41,920,715,595 1.67 percent
Piedmont: $3,027,278,586 $3,094,488,819 2.22 percent
Pleasanton: $17,326,290,380 $17,121,532,736 -1.18 percent
San Leandro: $9,654,888,215 $9,641,979,107 -0.13 percent
Union City: $7,849,794,994 $7,858,218,879 0.11 percent
*Unincorporated: $14,127,904,708 $14,239,266,288 0.79 percent
*Ashland, Castro Valley, Cherryland, Fairview, Hillcrest Knolls, San Lorenzo
Source: Alameda County Office of Assessor