Lake Ralphine, located in Santa Rosa, California, is a picturesque reservoir owned by the local government and primarily used for water supply. With a dam height of 35 feet and a storage capacity of 387 acre-feet, this Earth-type dam was completed back in 1882. The reservoir covers a surface area of 19 acres and has a drainage area of 0.15 square miles, drawing water from the nearby Tr Santa Rosa Creek.

Despite its age, Lake Ralphine is in satisfactory condition and is inspected regularly to ensure its safety. With a high hazard potential, the dam is regulated by the California Department of Water Resources under the Safety of Dams program. While its primary purpose is water supply, the reservoir also offers recreational opportunities to visitors. Overall, Lake Ralphine stands as a vital water resource in Sonoma County, serving both practical and leisurely purposes in the region.