CS36B - Concurrent Session 36B: The Lake Overholser Dam Failure of 1923 - Devastation in Oklahoma City

Lake Overholser Dam, located in the heart of Oklahoma City, Oklahoma along the North Canadian River consists of a buttressed concrete pumphouse with four arched sluiceway openings and buttressed spillway bays and a gated spillway concrete gravity section tied into earthen embankments. To this day, the dam impounds a 1,500-acre lake that serves as a critical water supply source and major recreational amenity for the city. However, on October 16, 1923, the lake became a threat to the community. That year, the city had suffered severe flooding from spring rains and it was happening again in October. These rains pummeled the watershed and caused lake levels to rise sharply and overtop and breach the earthen embankments on either end of the concrete structures. The observed initial failure point was the west embankment, causing the river downstream of the dam to rise by seven feet in approximately 30 minutes. Two more hours passed, and the east embankment was breached, causing the river to rise an additional two feet. Immediately after the failure of the west embankment, a 25-foot-high flood wave engulfed the city streets and inundated significant portions of the city. Urgent telephone warnings were made, and more than 300 members of the National Guard and American Legion volunteers worked to evacuate over 15,000 residents across 117 city blocks. These evacuations saved hundreds, if not thousands, of lives, but unfortunately five lives were lost and downstream damages, not only to Oklahoma City but also to several other communities as far downstream as 30 miles, exceeded $3M (1923 dollars). Recovering from the flood was a tall task that took months. As a part of the recovery and rebuilding effort, the City also worked to straighten portions of the river to help reduce future downstream flooding and the impacts associated with a dam breach. Thankfully, there has not been another dam breach and Lake Overholser continues to serve the residents of Oklahoma City, with multiple dam safety modifications and improvements currently planned or underway by the Oklahoma Water Resources Board to extend the service life of the structure.

This presentation will explore the critical nature of the dam and lake to Oklahoma City, the events surrounding the failure of the dam, the major undertaking to restore the City and mitigate future flooding impacts, and the current steps to improve the safety of this essential structure.