Emerald Lake, located in Robinson Township, Pennsylvania, is a private recreational lake regulated by the Pennsylvania Department of Environmental Protection. The dam at Emerald Lake, completed in 1912, is an earth dam with a height of 38 feet and a length of 130 feet. The lake has a storage capacity of 390 acre-feet, with a normal storage level of 276 acre-feet and a surface area of 18 acres.

Despite its age, the dam at Emerald Lake is in satisfactory condition and has a significant hazard potential. Regular inspections are conducted every two years to ensure the safety and integrity of the structure. The surrounding area, including the St. Patricks Run river and the Washington County, Pennsylvania, is a key location for water resource and climate enthusiasts interested in studying the impact of recreational water bodies on the local environment. With its peaceful setting and historical significance, Emerald Lake is a valuable resource for both recreation and research in the region.