Unnamed Tank, also known as Bat Tank, is a privately owned water storage facility located in Graham, Arizona. Managed by the Arizona Department of Water Resources, this earth dam structure serves multiple purposes including fire protection, stock watering, and as a small fish pond. With a dam height of 10.5 feet and a storage capacity of 52.5 acre-feet, the tank sits along the Whitlock Wash and covers a surface area of 10.2 acres.

Although rated as having a low hazard potential, Unnamed Tank has a moderate risk assessment due to its location and structural characteristics. Despite being uncontrolled, the tank's spillway boasts a width of 130 feet to manage excess water flow. The last inspection in November 2011 deemed the tank to be in satisfactory condition, with a periodic inspection frequency of 5 years. While the tank's emergency action plan and risk management measures are not fully documented, its state-regulated status ensures compliance with safety and environmental regulations.

Unnamed Tank stands as a vital resource in the semi-arid landscape of Arizona, providing essential water storage for firefighting efforts, livestock, and wildlife. As climate change impacts water availability in the region, the proper maintenance and regulation of such water structures become increasingly crucial to ensure sustainable water management practices in the face of evolving environmental challenges.