Big Dobe South, also known as Raker and Thomas Reservoirs, is a privately owned water storage facility located in Modoc, California. Completed in 1912, this earth dam stands at a height of 11 feet and has a storage capacity of 3860 acre-feet. The reservoir serves primarily for irrigation and water supply purposes, with a drainage area of 28 square miles and a surface area of 800 acres.

Despite being classified as a low hazard potential structure with satisfactory condition assessment, Big Dobe South is regulated and inspected by the California Department of Water Resources for dam safety. The reservoir is situated near the Tr Rattlesnake Creek in Big Sage Reservoir, within the Sacramento District. The dam's last inspection was conducted in August 2019, with a frequency of one inspection per year to ensure its continued safe operation.

This historic water resource infrastructure plays a crucial role in supporting agricultural activities in the region and maintaining water supply reliability. With its modest size and low hazard potential, Big Dobe South exemplifies the importance of proper maintenance and regulation to ensure the safety and efficiency of water storage facilities in the face of changing climate conditions.