The Taylorville Fire Department is containing a fuel-type oil that entered the pond at Manners Park through a storm drain.
Firefighters were called Thursday afternoon to the park.
The source of the oil was traced to a train depot north of the park.
Absorbent booms are being used to contain the oil.
An environmental cleanup contractor worked at the scene overnight, and the Illinois Environmental Protection Agency has been consulted.
The fire department says there is no current threat to the public. Manners Park is closed during the cleanup.
