Last Chance No. 1, also known as Upper Twin Lake, is a privately owned earth dam located in Westminster, Colorado. Completed in 1892 for irrigation purposes, this historic structure stands at 14 feet high and spans a length of 810 feet, with a storage capacity of 150 acre-feet. Situated on Big Dry Creek-OS, this dam serves multiple functions including fire protection, stock watering, and recreational use in addition to its primary irrigation role.

Despite its age, Last Chance No. 1 has a low hazard potential and is currently rated as not assessed for condition. The last inspection took place in 1986, with a moderate risk assessment given a ranking of 3. While the dam meets state regulatory requirements for permitting, inspection, and enforcement, there is no Emergency Action Plan (EAP) in place, indicating a potential area for improvement. Overall, this structure presents an intriguing blend of historical significance and modern challenges in water resource management.

For water resource and climate enthusiasts, Last Chance No. 1 offers a glimpse into the intersection of past engineering achievements and contemporary dam safety considerations. With its location in a picturesque setting in Jefferson County, Colorado, this dam serves as a reminder of the importance of maintaining and monitoring aging infrastructure to ensure both water supply reliability and public safety. As efforts continue to address potential risks and enhance emergency preparedness, Last Chance No. 1 remains a fascinating case study in the ongoing management of water resources in the face of changing environmental conditions.