Mary Stock is a private earth dam located in Johnson County, Wyoming, near the city of Arvada. Built in 1970 for fire protection, stock, or small fish pond purposes, this dam stands at 38 feet tall with a hydraulic height of 33 feet. With a storage capacity of 87 acre-feet and a surface area of 7 acres, Mary Stock plays a crucial role in water resource management in the region.

Despite its important function, the dam's condition assessment is rated as poor, with a low hazard potential. The last inspection in September 2017 indicated a need for improvements to ensure its structural integrity and long-term effectiveness. Although the risk assessment categorizes it as moderate, with a risk management plan in place, continued monitoring and maintenance are essential to mitigate any potential hazards and safeguard the surrounding area from flooding or other water-related issues.

As a key structure in the Arpan Draw watershed, Mary Stock is a focal point for water resource and climate enthusiasts interested in the intersection of water management, infrastructure sustainability, and environmental conservation. With its historical significance and current condition, this dam represents both a challenge and an opportunity for stakeholders to work together to ensure its resilience and continued contribution to the local ecosystem.