Lewis Dam, located in Union Mills, Iowa, along the TR-North Skunk River, was completed in 1963 by the USDA NRCS. This private dam serves primarily for fire protection, stock, or small fish pond purposes, with a height of 25 feet and a length of 327 feet. The dam has a storage capacity of 45 acre-feet, with a normal storage level of 25 acre-feet and a surface area of 4 acres. Despite its low hazard potential and moderate risk assessment, the dam's condition is currently not rated, and it is not regularly inspected.

Managed by the Iowa Department of Natural Resources, Lewis Dam is regulated, permitted, inspected, and enforced by state authorities to ensure its safety and compliance with regulations. The dam features an uncontrolled spillway type and is constructed with an earth foundation and soil core. While the dam has not been modified in recent years and lacks certain emergency preparedness measures, it remains a key structure for water resource management in the region. The dam's location, design, and purpose make it a vital component in the local ecosystem and water supply infrastructure.

Water resource and climate enthusiasts will find Lewis Dam intriguing for its historical significance, structural design, and environmental impact. As a privately owned dam with state oversight, Lewis Dam showcases the importance of balancing water management needs with regulatory requirements. With its unique characteristics and role in fire protection and stock pond maintenance, Lewis Dam serves as a focal point for understanding the intersection of human development and natural resource conservation in the context of climate change and water sustainability.