How did Walnut Creek stop the flooding downtown?

It didn’t happen overnight. While the city had struggled with traffic for decades, after Broadway Shopping Center opened in 1951, traffic came to a standstill on Main Street on Saturdays and weekday afternoons. Community leaders acknowledged the inadequacy of downtown street design and in 1954 drafted the Little Master Plan—a blueprint for street and traffic improvements. Among the changes it brought about was the creation of a new thoroughfare—Broadway—built upon a concrete culvert that channeled the waters of Walnut Creek.

 

As residents and motorists suffered through three years of roadwork from 1957-1960, natural disasters contributed to the grief, particularly another major flood in 1958, that forced evacuations, paralyzed downtown businesses, and caused $2-3 million in damages. 

 

When the Army Corps of Engineers was asked to help with the situation in the 1960s, the project further widened the already channelized creek and constructed levees to allow the water to rise higher without escaping. The Corps developed a plan involving a system of levees, drop structures, and concrete channels. Construction took six years. It began at Suisun Bay and proceeded upstream to Ygnacio Valley Road.

*Sources: Contra Costa County Public Works; Friends of the Creeks; Walnut Creek Historical Society; Walnut Creek An Illustrated History by Brad Rovanpera.