Colonial No 3 is a historic gravity dam located in Fayette, Pennsylvania, specifically in Jefferson Township along Washwater Run. Completed in 1907, this dam serves primarily for recreational purposes and stands at a height of 28.5 feet with a length of 161 feet. With a storage capacity of 26 acre-feet, it covers a surface area of 2 acres and has a drainage area of 1.5 square miles.

Owned privately, Colonial No 3 is regulated by the Pennsylvania Department of Environmental Protection, ensuring that it meets state inspection, enforcement, and permitting requirements. The dam has a low hazard potential and has not been formally assessed for its condition. The last inspection took place in November 2015, with an inspection frequency of every 5 years.

This historical structure provides a glimpse into the early 20th-century engineering practices while offering a recreational oasis for local residents and visitors alike. Its serene setting along Washwater Run makes it a tranquil spot for nature enthusiasts and water resource aficionados to appreciate the intersection of human ingenuity and the natural environment.