Magoon No. 1 is a privately owned earth dam located in Niobrara, Wyoming, along the Young Woman Creek. Completed in 1959 for irrigation purposes, this structure stands at 25 feet high with a hydraulic height of 20 feet, spanning a length of 508 feet. With a storage capacity of 593 acre-feet, the dam serves as a vital resource for water management in the region, storing up to 358 acre-feet of water during normal conditions.

Despite its age, Magoon No. 1 is considered to have a low hazard potential and is in fair condition according to a recent assessment conducted in July 2020. With a moderate risk assessment rating of 3, the dam is inspected every five years to ensure its structural integrity and safety. Equipped with a slide gate for outlet control, the dam also features an uncontrolled spillway with a width of 50 feet, allowing for controlled water release during times of high flow.

Managed by the Wyoming State Engineer's Office, Magoon No. 1 plays a crucial role in supporting agricultural activities in the area, highlighting the importance of maintaining and monitoring this essential water resource for both irrigation and flood control purposes.