The O'Neill Forebay Dike in California, managed by the Bureau of Reclamation, serves a primary purpose of hydroelectric power generation. This earth dam, completed in 1966, stands at a height of 16 feet and spans 1120 feet in length. It is situated on the San Luis Creek in Merced County, California, and has a maximum storage capacity of 64,800 acre-feet, with a normal storage level of 56,430 acre-feet.

Despite being classified as low hazard potential, the O'Neill Forebay Dike poses a high risk due to its condition assessment being marked as "Not Available." The dam has not been modified over the years, and there is no spillway in place. While it does not fall under state jurisdiction, the Bureau of Reclamation oversees its operations, inspections, and regulatory aspects. Emergency action plans have been prepared, but their compliance with guidelines and inundation maps are not currently available.

For water resource and climate enthusiasts, the O'Neill Forebay Dike represents an integral part of California's hydroelectric infrastructure. Its strategic location and design contribute to the state's renewable energy goals while also highlighting the importance of regular maintenance and risk management for dam safety. With its historical significance and ongoing operational oversight by federal agencies, the O'Neill Forebay Dike serves as a reminder of the critical role dams play in water resource management and climate resilience.