The Lummi Island Estates Dam, located in Whatcom County, Washington, is a private structure designed for recreational purposes and water supply. Completed in 1963, this earth dam stands at a hydraulic height of 28 feet, with a structural height of 26 feet. It has a normal storage capacity of 49 acre-feet and a maximum storage capacity of 67 acre-feet, serving the surrounding area in the Tr-Hale Passage watershed.

Managed by the Washington Department of Ecology, the Lummi Island Estates Dam is regulated, inspected, and enforced by state agencies to ensure its safety and functionality. Despite its high hazard potential, the dam's condition assessment in 2015 reported it as satisfactory. With a drainage area of 0.36 square miles and a surface area of 4.3 acres, this dam plays a crucial role in water management and recreational activities in the region.

For water resource and climate enthusiasts, the Lummi Island Estates Dam offers a fascinating example of a privately owned structure with significant implications for the surrounding ecosystem. Its presence in the Tr-Hale Passage watershed highlights the intersection of human infrastructure and environmental stewardship, serving as a critical piece of the region's water supply and recreational landscape. With ongoing state oversight and regular inspections, this dam stands as a testament to the careful balance between human needs and natural resource management in the Pacific Northwest.