Lyman Dam, located in St. Johns, Arizona, along the Little Colorado River, was completed in 1912 and serves as a crucial water resource for irrigation purposes. The dam is privately owned and state-regulated by the Arizona Department of Water Resources, with a height of 60 feet and a length of 800 feet. With a maximum storage capacity of 44,500 acre-feet and a normal storage of 30,600 acre-feet, the dam covers a surface area of 1,324 acres and has a drainage area of 790 acres.

The dam's spillway type is uncontrolled, with a width of 160 feet, and it has a maximum discharge capacity of 15,000 cubic feet per second. Despite its high hazard potential, Lyman Dam is currently assessed as being in satisfactory condition as of October 2017, with regular inspections taking place every year. The risk assessment for the dam is moderate, with a DSAC (Dam Safety Action Classification) rating of 3, indicating that risk management measures are in place to ensure the safety and reliability of the structure in the face of potential emergencies.

For water resource and climate enthusiasts, Lyman Dam presents an intriguing case study of a historic rockfill dam that continues to play a vital role in supporting agricultural irrigation and recreational activities in the region. With ongoing state regulation and maintenance efforts, the dam stands as a testament to the importance of proper infrastructure management in ensuring the sustainability of water resources amid changing environmental conditions.