South Tani Reservoir, also known as East Gravel Lakes, is a privately owned water supply reservoir located in Thornton, Colorado. Constructed in 2006 by GEI Consultants, this earth dam stands at a height of 22 feet, serving the primary purpose of water supply for the surrounding area. With a maximum storage capacity of 7,530 acre-feet and a normal storage capacity of 6,607 acre-feet, the reservoir covers a surface area of 228 acres and is fed by the South Platte River.

The dam, with a hydraulic height of 18 feet and a spillway width of 100 feet, has a high hazard potential but is in satisfactory condition as of the last inspection in December 2020. The risk assessment for the reservoir is moderate, indicating a level 3 risk. While the dam has not been modified over the years, it is regularly inspected and has emergency action preparedness plans in place. Overall, South Tani Reservoir plays a crucial role in water resource management in the region and highlights the importance of maintaining infrastructure for climate resilience.