Hepp is a privately owned irrigation dam located on Dry Creek in Johnson, Wyoming. Completed in 1964, this earth dam stands at 22 feet tall and spans 1070 feet in length. Its primary purpose is to provide irrigation water storage, with a normal storage capacity of 69 acre-feet and a maximum storage of 172 acre-feet.

Despite its low hazard potential and fair condition assessment, Hepp is subject to state regulation, inspection, and enforcement by the Wyoming State Engineer's Office. The dam features an uncontrolled spillway with a width of 100 feet and is equipped with a single slide gate for outlet control. The last inspection in July 2018 deemed the dam to be in fair condition, with a moderate risk assessment rating of 3.

Hepp serves as a vital resource for agricultural water management in the region, offering a reliable source of water for irrigation purposes. Its strategic location and design make it a key component of the water infrastructure in the area, contributing to the sustainability and resilience of the local agricultural sector. Despite being privately owned, Hepp plays a crucial role in water resource management and climate adaptation efforts in the region, highlighting the importance of maintaining and monitoring dams for long-term water security.