Lonesome Lake, located in Unity Township, Pennsylvania, is a privately owned recreational water resource regulated by the Pennsylvania Department of Environmental Protection. This earth dam structure, standing at a height of 24 feet and stretching 400 feet in length, serves the primary purpose of recreation with a storage capacity of 62.9 acre-feet. The dam, built on Brinker Run, a small stream with a drainage area of 0.5 square miles, has a low hazard potential but is currently assessed to be in poor condition.

Despite its poor condition, Lonesome Lake remains a popular spot for outdoor enthusiasts seeking recreational activities such as fishing, boating, and hiking in the Westmoreland County area. The dam has a normal storage capacity of 39.4 acre-feet and undergoes inspections every five years to ensure its structural integrity and safety. With its picturesque surroundings and diverse wildlife, Lonesome Lake continues to attract visitors who appreciate the beauty of this man-made water feature in a natural setting. Climate and water resource enthusiasts can explore the unique ecosystem of Lonesome Lake while also advocating for its preservation and improvement to enhance the recreational experience for future generations.