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It is surrounded by the Chatsworth Reservoir in the north, Canoga Park in the east, Woodland Hills in the south, Hidden Hills in the southwest, and the Simi Hills in the west. The postal codes are
There are several small tributaries of the Los Angeles River that originate in the Northwest San Fernando Valley. The Los Angeles River itself begins at the confluence of Calabasas Creek and Bell Canyon Creek, and the latter of these runs through West Hills. These and other small creeks supply runoff water to the Los Angeles River, and several are considered year round creeks. Although the creeks are now channeled and run within concrete walls, they do form a significant urban wildlife landscape and contribute to the population of indigenous wildlife left within the San Fernando Valley. Dayton Creek in particular has received attention due to its vicinity to the Santa Susana Field Laboratory, which is under field cleanup due to its fundamental use as a testing center for rocket and missile fuel, nuclear power research, and high technology defense systems. Contaminants include Chromium, Lead, Benzene, and many other components of rocket fuel.