New York’s Department of Environmental Conservation says a whiskey-aging facility in Moriah must apply for an air emissions permit by the end of October.

The DEC’s decision concerns WhistlePig Whiskey’s warehouses in the Mineville hamlet, where residents have reported gummy black deposits on nearby homes and businesses. The substance is a fungus known as Baudoinia compniacensis, which can grow on surfaces exposed to ethanol vapor released during the whiskey-aging process. The DEC says it does not believe the deposits pose a health hazard.

In a letter to Moriah Ventures LLC, a WhistlePig subsidiary, DEC Regional Engineer Yuan Zeng said the company operates at least 11 aging warehouses at the site and has approval to build three more. Based on the company’s estimate of 14,000 barrels per warehouse, the facility could hold at least 154,000 barrels. The DEC estimates its potential ethanol emissions at about 531 tons a year—well above the 50-ton threshold for a major source of volatile organic compounds.

The permit, known as an Air Title V permit, is issued jointly by the DEC and the U.S. Environmental Protection Agency. Zeng said the EPA has determined that emissions of volatile organic compounds from spirit-aging facilities can be regulated.

WhistlePig has previously denied that its Mineville warehouses caused the deposits. As a gesture of goodwill, it agreed to pressure-wash homes within 900 feet of the facility. Filtering the emissions could reduce the deposits, but distillers say filtration may also affect the whiskey’s taste.

WhistlePig ages and stores its whiskey in Moriah and bottles it in Shoreham, Vermont.