Anderson No. 1 is a privately owned earth dam located in Niobrara, Wyoming, near the city of Edgemont, SD. Completed in 1959, this dam serves multiple purposes including fire protection, stock watering, and as a small fish pond. The dam has a height of 24 feet, a hydraulic height of 19 feet, and a structural height of 26 feet, with a length of 270 feet and a storage capacity of 48 acre-feet.

Despite being classified as having a low hazard potential and fair condition assessment, Anderson No. 1 is regulated and inspected by the Wyoming State Engineer's Office. This uncontrolled spillway dam on Sours Draw has one outlet gate and is situated in a drainage area of 0 square miles. The dam's risk assessment is categorized as moderate, and it undergoes inspections every five years, with the last assessment conducted in May 2018.

Overall, Anderson No. 1 presents an interesting case study for water resource and climate enthusiasts, showcasing the intersection of private ownership, state regulation, and the practical applications of earth dam infrastructure. With its historical significance dating back to the late 1950s and its continued operation for fire protection and livestock management, this dam serves as a valuable asset in the region while also posing manageable risks that necessitate regular inspection and maintenance protocols.