Officials from the Pittsburgh Zoo visited Beaver Run Reservoir in Slickville on Tuesday in hopes of spotting the reptile.
Zoo reptile curator Henry Kacprzyk says he's confident the wire trap will catch the alligator, which officials believe was a pet that someone turned loose.
The alligator was first spotted about a month ago. Officials scrapped a plan to let it succumb to the cold weather after public outcry.
The Municipal Authority of Westmoreland County reservoir has about 25 miles of shore line. Kacprzyk says the trap will be set up on a sunny spot near where the alligator was last seen.