Lake Mission Viejo, located in Mission Viejo, California, is a privately owned reservoir on Oso Creek that serves primarily as a water supply source. Built in 1976, this earth-type dam stands at 123 feet in height and spans 1750 feet in length, with a storage capacity of 4300 acre-feet. The reservoir covers a surface area of 150 acres and has a drainage area of 3.6 square miles, making it a vital resource for the local community.

Despite its primary purpose of water supply, Lake Mission Viejo also offers recreational opportunities for residents and visitors to enjoy. With its picturesque setting and varied activities such as boating and fishing, the reservoir serves as a popular destination for outdoor enthusiasts. The dam's satisfactory condition assessment and high hazard potential highlight the importance of regular inspections and emergency preparedness to ensure the safety and security of the surrounding areas.

Managed by private owners and regulated by the California Department of Water Resources, Lake Mission Viejo plays a crucial role in sustaining the region's water resources and supporting the needs of the community. With its strategic location and significant storage capacity, this reservoir stands as a key asset in managing water supply and promoting resilience in the face of changing climate conditions.