Biological Summary Ahmanson Biological Summary Taken from the final Ahmanson EIR Ahmanson Ranch occupies 5,477 acres in the southeastern portion of the Simi Hills. The Simi Hills form a isthmus between the Santa Susana Mountains to the and the Santa Monica Mountains to the south at the western boundary of the San Fernando Valley. Topograpgy of the Simi Hills is complex, ranging from virtually flat mesas and valleys to near vertical rock outcrops in the northern areas. Physiography of the Simi Hills is related to the local and regional geologic history, weathering characteristics of the parent materials and established natural drainage patterns. Large areas of the Simi Hills presently exist as relatively undisturbed open space although grazing has historically occurred over most if not all of the area.
Soils range from absent or thin veneers in rocky areas to several feet in valley bottoms.
The climate of the region is characterized as Mediterranean with cool moist winters and warm dry summers. The nearest climatic station to the project site is Canoga Park at Pierce College, six miles east of the site. Average precipitation for this time period is 16 inches. Temperature and precipitation vary considerably from location to location and areas within Ahmanson Ranch may differ from each other owing to the diverse topography of the site. Fire has historically played a major role in the Simi Hills.