In ancient times, the Brea Creek was no doubt utilized by the Native American Indian people, known in their indigenous tongue as the ‘Tongva’, which means people of the earth and later referred to by the Spanish as the ‘Gabrieliño’, that inhabited the La Habra valley for the past 10,000 years. Brea was then within the ethnographic boundaries of the Tongva; their village was called Nacaunga in the Tongva language and was strategically located at the mouth of the Brea Canyon adjacent to the Brea Creek.
Colonial times
In colonial times, on Saturday, July 29, 1769, the Spanish explorer Don Gaspar de Portolá i Rovira along with Father Junipero Serra and others such as José Antonio Yorba camped at la Brea Canyon north of Fullerton within the La Habra Valley region near a stream and near a canyon called in the Spanish tongue ‘La Cañada de la Brea’, having crossed the Santa Ana River along ‘El Camino Real’, which ran through Anaheim, Fullerton, Brea and La Habra on their famed march from San Diego to Monterrey. Moreover, most of the waterways in the Orange County area received their name from Spanish Conquistadores in the 18th century.
Course
The creek begins in the northeasternmost part of the Coyote Creek drainage basin, in a mountain canyon named Brea Canyon, at the Los Angeles County–San Bernardino County line. It flows southwest, receiving over ten small right-bank tributaries, before crossing the Orange County–Riverside County line and receiving Tonner Canyon on the left bank. The creek bends northwest then sharply southwest, receives a few more tributaries on either bank, and flows into the northernmost arm of Brea Reservoir. Exiting the Brea Reservoir dam, the creek bends west-northwest in a straight and channelized course, receives several small right-bank tributaries, flows past a retention basin on the left bank, and joins Coyote Creek shortly upstream of Fullerton Creek, the next major tributary.
Streamflow
From 1932 to 1969, the USGS operated two streamflow gauges on Brea Creek, one at the mouth and one at Brea Reservoir. The highest flow recorded at the mouth was on 14 March 1941. Four other flows during that period exceeded 1,000 second-feet, all before 1941.
River modifications
There are four drop structures on Brea Creek, all of which are built of reinforced concrete, in the lower course of the creek, which is referred to as the "Brea Canyon Channel".
