About 1,500 gallons of de-icing fluid leaked yesterday morning from an above-ground storage tank at Baltimore-Washington International Airport - some of it making its way into Kitten's Branch, a tributary of the Patapsco River.
The stream water turned a coffee-brown color, but the liquid did not pose an immediate public danger, said Richard J. McIntire, a Maryland Department of the Environment spokesman.
Hazardous-materials crews from the airport and Anne Arundel County fire departments plugged the leaking 100,000-gallon tank, which is at the end of one of BWI's runways.
The leak was caused by a loose roof shingle that hit and broke a measuring device on the tank, McIntire said.
The crews were able to absorb some of the spilled propylene glycol, which at different concentrations is used in toothpaste and some cake mixes.
The rest of the water-soluble liquid was flushed through a storm drain, he said.
Well water should not be affected by the spill, but it is dangerous to fish in the stream, though no fish kill was reported.
McIntire said the toxin barely registered in water tests downstream but that residents who live near the stream should keep pets away from the polluted water and might notice foam in the water and an onion-like smell.
Officials said the water will be tested again today.