Sinlahekin Dam No 3, also known as Conners Lake, is a state-owned structure located in Loomis, Washington, along the Sinlahekin Creek. Built in 1950 by URS-Woodward Clyde, this earth dam stands at a hydraulic height of 24 feet and a structural height of 22 feet, with a length of 285 feet. The dam serves primarily for recreational purposes, providing a storage capacity of 593 acre-feet and a surface area of 211 acres.

The dam is regulated by the Washington Department of Ecology and undergoes regular inspections, with the last assessment conducted in 2016. Despite its high hazard potential, the condition of Sinlahekin Dam No 3 is deemed satisfactory. Emergency action plans are in place but may require updates to meet current guidelines. The dam's risk assessment and management measures are currently unspecified, highlighting the importance of ongoing monitoring and maintenance to ensure its safety and functionality for water resource and climate enthusiasts in the region.

Overall, Sinlahekin Dam No 3 plays a vital role in providing recreational opportunities while also serving as a crucial infrastructure for water management in Okanogan County, Washington. Its historical significance, coupled with its ongoing regulatory oversight and maintenance efforts, underscore the importance of sustainable practices in safeguarding water resources and addressing climate-related challenges in the region.