This year's craft brewer list includes three other North Coast breweries: Bear Republic, which fell two spots to 36; Lost Coast, which rose one spot to 37; and North Coast, which fell three to 45.

As with last year, the top spot was held by Boston Beer Company, maker of the Sam Adams line. California's Sierra Nevada remained at number two, while Colorado's New Belgium and Texas-based Gambrinus held steady at three and four.

The exploding volume at Lagunitas has Magee thinking even bigger. He said he is already contemplating a third brewery somewhere in the U.S., possibly as soon as 2017, and eventually building or acquiring a brewery in Europe to meet burgeoning demand for American beers.

Lagunitas beer is distributed in 36 states, with 10 more ready to join once Chicago production ramps up, he said. Magee is also in discussions with a number of chain stores that he previously was unable to supply because the Petaluma plant didn't have room to expand.

The expansion plans "can seem like real, crazy ambitious," he said, "but there is a real linearity to it," given the growth of the company and craft brewing in general.

At the same time sales of major brands such as Budweiser and Coors are stagnating or falling, flavorful brews from smaller producers are surging. Beer sales volume nationally grew only 1 percent last year overall, but the craft segment grew 18 percent. It now accounts for 7.8 percent of all beer sold in the U.S., up from 6.5 percent the previous year.

Lagunitas' growth, even as it expands production elsewhere, is good news for Sonoma County, said Ben Stone, director of the county Economic Development Board.

"Traditionally wine has been our calling card," he said. "Now we're seeing, with Lagunitas in the forefront, craft beer be a calling card."