[6][7] Brea Creek begins in the far northeastern corner of the watershed, at the border of Los Angeles and San Bernardino counties.

The creek then proceeds to enter increasingly urbanized landscape, then flows into Brea Reservoir, which functions mainly for flood control.

Shortly downstream from the confluence, it is joined by its North Fork, or La Canada Verde Creek.

The creek sharply turns due west, and continues winding through predominantly residential suburbs, before flowing into Coyote on the left bank.

[6][7] The United States Geological Survey (USGS) operated two stream gauges on Coyote Creek.

From 1965 to 1978, the USGS recorded flows at Los Alamitos, California, which is at its confluence with the San Gabriel River.

In that time period, no other flow passed 1,000 cfs, although it did come close to on 2 March 1938 (the peak of the Los Angeles Flood of 1938).

[12] Although channelized in many areas along its course, Coyote Creek and its tributaries provide some rich habitat for riparian and other species, including salt marsh instream, as well as coastal sage scrub, live oak, grassland and sand dunes.

Native wildlife is common in the areas described, especially in the far upper reaches of the watershed, which include Brea and Tonner canyons.

[7] The Army Corps of Engineers expanded the channel and lined the creek with concrete beginning in the early 1960s.

A young boy drowned in 1963, while playing on a makeshift raft, on the water behind a temporary dam built for the project.