SNOQUALMIE PASS -- About 9,000 gallons of deicer leaked out of a storage container and into the environment near Hyak.
Washington State Department of Transportation officials said crews discovered the leak at 3:00 a.m. Thursday and stopped the spill to contain the remaining 5,000 gallons in the tank.
The magnesium chloride leaked into the soil surrounding the tank and into the South Fork of the Snoqualmie River. Officials said the deicer is a non-hazardous chemical and its impact on the environment is considered minimal.
The cause of the leak was discovered as a broken fitting to the tank's shut-off valve. Crews are investigating how the valve broke.
The storage tank is four years old. Tanks that hold highway deicer are typically replaced every 15 years.