Roche Harbor Lake Dam, also known as Briggs Pond, is a privately owned earth dam located in San Juan, Washington. Built in 2013 by Bennett Engineering, this dam serves the primary purpose of water supply, with a capacity to store up to 629 acre-feet of water. It stands at a hydraulic height of 14.5 feet and a structural height of 12.5 feet, providing a vital reservoir for the surrounding area.

Situated on the Tr-Westcott Bay, Roche Harbor Lake Dam plays a crucial role in managing water resources in the region. With a surface area of 28 acres and a drainage area of 0.76 square miles, the dam has a maximum discharge capacity of 271.6 cubic feet per second. Despite its high hazard potential, the dam is in satisfactory condition as of the last inspection in April 2019, ensuring the safety and security of the local community.

In the event of an emergency, the dam has an Emergency Action Plan (EAP) in place, meeting regulatory guidelines and ensuring preparedness for any potential risks. With a history of modifications in 2008 to enhance its structural integrity, Roche Harbor Lake Dam stands as a vital infrastructure for water supply and climate resilience in the region, under the regulatory oversight of the Washington Department of Ecology.