Margaret Lake Dam, located in King County, Washington, is a privately owned structure that serves primarily for recreational purposes. Built in 1933, this earth dam stands at a hydraulic height of 41 feet and has a structural height of 38 feet, with a length of 480 feet. The dam has a storage capacity of 1210 acre-feet, with a normal storage level of 820 acre-feet. It spans the Margaret Creek and covers a surface area of 52 acres, contributing to the overall watershed's drainage area of 2.86 square miles.

Despite its age, Margaret Lake Dam is still in fair condition, as assessed in July 2020, with a high hazard potential due to its location and storage capacity. The dam has undergone inspections every five years, as per regulatory requirements by the Washington Department of Ecology. The structure has no outlet gates or spillway type specified in the data, indicating potential limitations in its ability to manage water discharge during high flow events. With its historical significance and recreational value, the dam continues to be an important feature in the region, requiring careful monitoring and maintenance to ensure public safety and environmental protection in the face of changing climate conditions.