The Department of Energy and Environmental Protection responded to an oil spill in Sympaug Brook in Danbury.
DEEP officials said the spill resulted from a hose failure at a manufacturing facility owned by Stanley Engineered Fastening on Shelter Rock Lane.
About 1,800 gallons of waste oil containing metals was assumed lost, and while some waste was recovered from a secondary containment, some released into the brook, DEEP said.
The spill resulted in a milky-white color, according to DEEP.
The manufacturing facility took responsibility for the clean-up and Moran Environmental Recovery and Full & O'Neill are assisting, DEEP officials said.
DEEP said they will continue to assess the situation and issue updates as needed.