Historical Floods

This section is intended to provide information about floods in California's past. Historical information regarding previous floods is essential in developing our understanding of current floods. Have earlier floods been larger or smaller? How big can floods get? We ask these questions in order to try to predict the size of floods and to give warnings about the potential flood risk. The goal is to protect life and property from flooding.

The first flood reported in California occurred on the Los Angeles River in 1770.

H. B. Lynch
Rainfall and Stream Run-off in Southern California Since 1769
Metropolitan Water District of Southern California, August 1931, p. 2

Synopsis of California's Flood Measurements

Written accounts of floods began with the arrival of Spanish missionaries to Southern California in 1769. California's first rainfall measurements were recorded in 1847. James W. Marshall discovered gold in 1848 on the South Fork of the American River in northern California. The influx of people brought individuals and the U.S. Army, which in 1850 started measuring rainfall in San Diego. (Lynch, 1931, p. 5) Since 1850, rainfall measurements have been taken in Sacramento, San Francisco, and San Diego.

Contents of This Section

Resources available to researchers are included in this section and organized into different areas as follows: