During a period when the average growth rate of San Mateo County's assessed property value is 3.3 percent, Atherton officials are smiling with the news that the town's rate of growth from fiscal year 2011-12 to this fiscal year is 9.03 percent.

A report by HDL Services, commissioned to answer questions town officials had about the share of property taxes it was receiving from the county, shows that the growth rate in Atherton's assessed property value is the highest in the county.

Coming in second on the list is Portola Valley, with a 5.25 percent growth rate. Also above the county average are Menlo Park, with 4.4 percent growth; and Woodside, with 4.2 percent. The growth rate in Hillsborough, also known for its high property values, was 4 percent.

Two cities are still suffering a loss in assessed value: East Palo Alto, at -2.5 percent; and Brisbane, at -0.46 percent.

In dollar terms, Atherton's net taxable assessed value of 2,619 parcels increased by about $575 million during this period, according to a report by Robert Barron, the town's finance director. That brings the total figure to $6.95 billion, the report says.

The largest assessed value increase in the town was on a purchase of four Atherton Avenue residential and vacant sites by 237 Atherton Avenue LLC and 246 Atherton Avenue LLC. The purchase price was $53 million, according to the HDL report, which listed the original combined values of the properties at $1.98 million.

During a recent meeting of the town's Finance Committee, Paula Cone of HDL Services was asked who owns the four Atherton Avenue parcels, to which she replied that, because of the trend of buyers creating limited liability companies (LLCs) as vehicles for land purchases, "I can't figure out who owns them."

The HDL report listed the top 10 property taxpayers in town, with the Atherton Avenue LLCs listed first. The next four top property taxpayers are, from two to five: philanthropist Bita Daryabari, George R. Roberts Trust, Pacific Peninsula Group, and 383 Associates LLC.

In addition to the Atherton Avenue property sale's contribution to the growth in property value, residential uses of property grew by 8.6 percent; "these were primarily homes that sold for more than the prior assessor's enrolled value," according to the report.

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