[3] Many tributaries feed the mostly free flowing, 17.3-mile (27.8 km) creek,[4] which is largely contained in the Matilija Wilderness.

The smaller North Fork Matilija Creek[7] flows west and south from its headwaters near Rose Valley.

Fed by some perennial springs, despite its location in arid terrain, the creek flows year round, and can flood severely following winter storms.

The Robles Diversion Dam on the Ventura River downstream posed a barrier to trout migration until a $6 million fish ladder was constructed in 2006.

The dam was notched to reduce its height twice in the late 20th century, in order to allow some of the accumulated sediment to flow downstream.