Connoquenessing Creek is a tributary of the Beaver River, approximately 50 mi (80 km) long, in Western Pennsylvania in the United States.

It receives Slippery Rock Creek from the northwest near Ellwood City, then joins the Beaver west of Ellwood City, approximately 3 mi (5 km) further downstream.

The steelmaker legally discharged more than 29 million pounds of nitrate compounds -- a waste produced when nitric acid is used to "pickle" or clean the surface of raw steel—into Connoquenessing Creek.

"[4] However, as of 2010, the Connoquenessing Creek was not listed in the national Top 10 for polluted waterways.

Also, as of 2010, Armco Inc. steel in Butler was not listed in the Top 20 in regards to national pollutant dischargers.