Each winter, beer lovers from across the United States and beyond line up in downtown Santa Rosa when Russian River Brewing Company releases its cult-classic ale, Pliny the Younger.

The extra hoppy "triple IPA," rated by one U.S. website as the best beer in the world, typically sells out within two weeks. But demand for Russian River's other brews has grown so strong that the Santa Rosa company has reached production capacity and doesn't have enough suds to supply its current list of restaurants and bars.

Craft brew aficionados in Washington state may have cried in their beer last week after learning that Russian River won't be sold there any longer. The company ended distribution in Washington last month after more than four years in the Evergreen State.

"We pulled out of Washington simply because we don't have the beer," said Natalie Cilurzo, who owns Russian River with her husband, renowned brewer Vinnie Cilurzo. "We need it at home because of the pub. That beer is going straight to the pub."

The pub, located on Santa Rosa's Fourth Street, will draw special attention next month as the Sonoma County Economic Development Board seeks to quantify the economic benefit of Pliny the Younger, slated to be released Feb. 1. Researchers will randomly survey patrons, who in past years have come from Scotland, Japan and Denmark.

The survey is part of a larger study this spring on the county's craft breweries, micro distillers and cider producers.

The sector is producing jobs and drawing new attention to a county best known for its wine, said Ben Stone, the board's executive director. And when he happened upon last February's Pliny release, he beheld "the longest line I'd ever seen downtown."

The survey will take place after Russian River's pub enjoyed a brisk Christmas season, with business up 60 percent from a year earlier. And it comes as the Cilurzos are talking together about whether and how they might expand production from their current level of 14,000 barrels a year. Natalie Cilurzo said the couple is "in the middle of the evening discussion phase" and wants to take time to develop a well-thought-out solution.

"We probably need to make a decision in 2013," she said. An expansion could cost between $10 million and $20 million, an amount of debt she considers sobering.

The 70-employee Russian River is known for making world-class beers and for taking a controlled approach to growth.

"They're one of the best breweries in the world, and they're doing this on their own terms," said Ken Weaver, a Petaluma author who wrote "The Northern California Craft Beer Guide."

The Cilurzos, both in their 40s and with years in both the beer and wine industries, came to Sonoma County in 1997 when Vinnie Cilurzo became the brewer for Russian River, then owned by Korbel Champagne Cellars. The couple bought the brew company from Korbel and opened their downtown brew pub in 2004.

In 2008 they opened their production brewery in south Santa Rosa, a move that allowed them to triple their output and greatly expand distribution. While no longer shipping beer to Washington, they still work with distributors in Southern California, Portland, Denver and Philadelphia.

Natalie Cilurzo has indicated that Washington was selected as the place to pull back from because of the difficulty of "managing our brand" there, due to some unique liquor laws. Even so, she expressed a desire one day to resume business there.

The brew pub's sales have quadrupled since opening nine years ago and account for more than half of Russian River's total business. Thus, making sure the pub has enough beer remains a priority for the company.

The Beer Advocate website rates Pliny the Younger No. 1 among the world's beers, and Russian River's Pliny the Elder, a Double IPA offered year round, at No. 6.

RateBeer, another site for which Weaver is editor of the weekly newsletter, puts Pliny the Younger at No. 4 and Pliny the Elder at No. 19.

Vinnie Cilurzo is widely regarded as the creator of the double IPA. He also has won praise for making brews with freshly picked "wet hops," for aging beer in North Coast wine barrels and for using "spontaneous fermentation," meaning the brewer doesn't add yeast but allows the beer to naturally collect wild yeasts and bacteria before fermenting in barrels.

Success in these areas led Cilurzo to receive an award for innovation from the Brewers Association in 2008.

"Vinnie is ultimately an artist," said Weaver.

Craft beer is a small but growing segment of the nation's $96 billion beer industry. Sales rose to $8.7 billion in 2011, up 15 percent from the previous year, while the overall market dipped 1 percent, according to the Brewers Association.

About 250 new U.S. breweries opened their doors in 2011, bringing the total to more than 2,100, the highest total since the 1880s. Three decades ago there were fewer than 100.

The Economic Development Board is preparing to hold a conference on craft breweries and related businesses in the fall, Stone said. The aim is to report on the significance of local craft breweries and the opportunities they could provide for economic growth.

Stone likened the region's craft breweries to the wine industry 35 years ago. That doesn't mean craft brewers will become as big a player in the county's economy, but "the engine's picking up speed," he said.

The county's biggest craft beer company is Lagunitas Brewing Co., which last year completed a $10 million expansion at its Petaluma facility and announced plans to build a similar plant in Chicago at a cost of $15 to $18 million. The latter expansion, expected to be completed this spring, will give Lagunitas the capacity to produce a total of 1.2 million cases a year, placing it among the ranks of the nation's largest craft brewers.