DENVER (CN) – A Colorado craft brewery blamed contaminated yeast for a $2 million recall of stout and two IPAs, and sued its yeast supplier earlier this week.

Represented by Maureen Whit of Holland & Hart, Indian Peaks Brewing – which does business as Left Hand Brewing – brought the complaint in Boulder County, Colorado, on Tuesday. It says White Labs “caused secondary fermentation in beers brewed using that yeast, including Milk Stout Nitro, resulting in over-pressurized bottles, broken bottles, off flavors, and disruption of the distinctive nitrogen cascade.”

According to Craftbeer.com, a nitrogen cascade occurs when a stout carbonated with nitrogen is poured and “the waterfall of tiny bubbles slowly yields to a dark brew with a fluffy, white head thick enough to float a bottle cap.”

In addition to its flagship Milk Stout Nitro, Left Hand says its Extrovert IPA and Warrior Fresh Hop IPA were also affected.

“It is unfortunate we had to file a lawsuit, but we didn’t have a choice. As an employee-owned brewery, the fate of our brand and employee livelihood was compromised and we are asking White Labs to take responsibility for the quality of their product and stand behind their guarantee,” said Eric Wallace, Left Hand’s co-founder and CEO.

Throughout 2016, Left Hand received numerous customer complaints over “abnormally high pressure and gushing beer,” according to the complaint In addition to discovering an increase in alcoholic content in its Milk Stout Nitro, brewers found that Extrovert IPA “exhibited phenolic characteristics.”

In other words, the beer didn’t taste right.

Left Hand’s operations in Longmont were halted for two weeks in September and October 2016, “ceasing production of all beer, disassembling all production equipment and rebuilding all valves and pipe pathways in an effort to discover and correct the cause of the contamination,” the brewery says in its complaint.

“Left Hand’s entire team of brewers and maintenance personnel worked day and night to make sure every single soft gasket, pipe junction, automated venting tank top, and basically every nook and cranny of the brewery was inspected, cleaned, and repaired,” the brewery says.

Left Hand says it finally took another brewer’s suggestion and conducted a DNA test on store-bought Milk Stout Nitro. The company discovered the stout was contaminated by a wild strain of yeast unfit for brewing beer, the Saccharomyces cerevisiae variant diastaticus.

Despite White Labs’ certificate of quality assurance, Left Hand says it consistently found diastaticus in beer brewed with yeast purchased from White Labs.

In addition to claims of negligence and breach of warranty, Left Hand also blames White Labs for the downturn in business, saying that following the incident “the market share and consistently increasing sales of Milk Stout Nitro significantly decreased.”

Until the recall, Left Hand says their signature stout was a top seller as “the first bottled, nitrogenated beer in the U.S. craft beer industry.”

According to their website, Left Hand is the 44th largest craft brewery in the United States and holds numerous accolades including 28 Great American Beer Festival medals, 11 World Beer Cup awards and 9 European Beer Star awards.

The brewery seeks actual, compensatory, punitive and treble damages.

White Labs did not immediately respond to requests for comment.