No. 5a, also known as the Enl of 7687r, is a private earth dam located in Sweetwater, Wyoming, near the Flaming Gorge Reservoir. Constructed in 1975 by designer Frank J. Trelease, this dam serves primarily for tailings storage, with a height of 58 feet and a hydraulic height of 52 feet. It spans 3,500 feet in length and has a storage capacity of 5,556 acre-feet, making it a key structure for managing water resources in the area.

The dam's spillway, operating as uncontrolled with a width of 30 feet, ensures the safe release of water during peak flows. Despite its low hazard potential and fair condition assessment, the dam undergoes inspections every five years to ensure its integrity and resilience. With a moderate risk assessment rating, No. 5a represents a crucial component of water resource infrastructure in Wyoming, playing a vital role in mitigating flood risks and safeguarding downstream communities along the Allied Draw river.

Owned and regulated by private entities, this earth dam stands as a testament to engineering excellence and effective water management practices. Its strategic location near the Flaming Gorge Reservoir underscores its importance in the region's water supply and storage network. As climate change continues to impact water resources, No. 5a serves as a critical asset in ensuring the resilience and sustainability of Wyoming's water infrastructure for future generations of water resource and climate enthusiasts.