Marys Lake Dike No. 1 is a federally-owned structure located in Larimer, Colorado, near the city of Estes Park. Built in 1948 by the Bureau of Reclamation, this earth dam stands at a height of 29 feet and spans 820 feet in length. Its primary purpose is for hydroelectric use, with a storage capacity of 1,149 acre-feet and a normal storage level of 927 acre-feet.

The dam sits on the Fish Creek Tributary and is regulated by the Colorado Department of Water Resources. With a high hazard potential and risk assessment rating of 2, Marys Lake Dike No. 1 undergoes regular state inspections and enforcement to ensure its structural integrity and safety. Although no spillway is present, the dam's construction on rock foundations and use of arch core types contribute to its stability.

Water resource and climate enthusiasts fascinated by hydroelectric infrastructure will appreciate the historical significance and engineering details of Marys Lake Dike No. 1. Its critical role in water management and energy production underscores the importance of maintaining and monitoring such structures in the face of changing climatic conditions and evolving regulatory requirements.