Toxic chemical releases from Sonoma County industries have declined steadily for six consecutive years, confirming the county's reputation as a magnet for clean business.
Industrial pollution dropped 76 percent from 27,950 pounds in 2007 to 6,801 pounds in 2012, according to a federal government report.
Going back nearly a quarter century, local industries released 332,508 pounds of toxics in 1988, the year the Environmental Protection Agency began tracking chemical emissions.
The steep decline is driven by a mix of factors, including changes made by some companies to clean up their production processes, the closure of other operations or their move out of the county, and the North Bay's long bid to build and recruit a wider network of businesses with a light toxic footprint.
"I think we have a lot of good corporate citizens in terms of the environment," said Ben Stone, executive director of the Sonoma County Economic Development Board.
The EPA's latest report — called a Toxics Release Inventory — also documents declining industrial pollution in California and the nation, although agency officials said the annual survey does not assess the risk that chemical releases pose to the public.
It does not assess chemical use by agriculture, nor does it address other pressing issues, such as the interaction of various pollutants and the growing presence of pharmaceuticals and other consumer products in the environment.
Curtailing those releases and their effects on human and environmental health is a top priority among watchdogs, said Stephen Fuller-Rowell, co-founder of the Sonoma County Water Coalition
But, he acknowledged, "this is still a pretty nice, clean place to live" and that helps "boost the local economy."
Three Sonoma County facilities — the Coast Guard base at Two Rock, Asti Winery outside of Cloverdale and Clover-Stornetta Farms in Petaluma — together accounted for most of the release or disposal of 6,801 pounds of chemicals in 2012.
Two other firms released less than 100 pounds combined.
The EPA defines a release as the amount of a toxic chemical released to the air, water and land on site as well as the transfer of chemicals for off-site disposal.
Sonoma ranked 32nd among California counties, producing a tiny fraction — 0.02 percent — of the 31.7 million pounds of pollutants released statewide, the EPA said.
California ranked 30th out of 56 states and territories in toxic releases, which generally have declined since 2001, an EPA official said.
Back in 1988, Agilent Technologies, the North Bay's largest technology employer, was also the largest source of toxic releases, reporting 155,870 pounds of chemicals, nearly half the county's total at the time.
Agilent no longer releases any toxics, officials said.
The company, formerly part of Hewlett-Packard, spent four years and more than $60 million developing substitutes for ozone-depleting chemicals, including freon and 1.1.1-trichloroethane, said Tricia Burt, Agilent's environmental health and safety manager.
Agilent reported releases of the two chemicals from 1988 to 1992.
It also reported release of acetone from 1988 to 1993 and still uses it, but acetone has been dropped from EPA's list of reportable chemicals, she said.
Agilent reported the release of 10 pounds of nitric acid in 1993 and still uses it, but none is released to the environment, Burt said.
Releases under the EPA reporting program refer to normal usage of chemicals, not to spills or other accidental discharges, the company said.