Bell Creek and Arroyo Calabasas are the headwaters of the Los Angeles River, by name its beginning with their confluence in nearby Canoga Park.

Riparian zone plants include California sycamores (Platanus racemosa) and arroyo willows (Salix lasiolepis).

Spring wildflowers include the redbush monkey flower (Mimulus aurantiacus), Plummer's mariposa lily (Calochortus plummerae), and canyon sunflower (Encelia californica).

The Simi Hills are a critical wildlife corridor linkage for the Santa Monica Mountains to these and other Transverse Ranges further east.

The undeveloped native habitat provides routes that protect larger land wildlife of the Santa Monicas from genetic isolation.

[5][6] The Wallis Annenberg Wildlife Crossing is a proposed vegetated overpass spanning the Ventura Freeway at Liberty Canyon in Agoura Hills, California.

[citation needed] The Juan Bautista de Anza expedition passed through the area in 1769, being the first European sighting of the Simi Hills.

[13] In 1845 the land grant for Rancho El Escorpión, beside the Peak and named for it, was issued to one Chumash and two Tongva people and a rare instance of Native Americans being grantees, by Mexican Governor Pío Pico.

[citation needed] In the first half of the 20th century, there were four large movie ranches in the Simi Hills for filming motion pictures on location.

Hillside subdivisions regraded natural contours into terraced lots, changing the Hills viewshed, drainage patterns, and habitats in those areas.

[15] The Rim of the Valley Trail Corridor[16] is in the planning stages and includes the Simi Hills open space parklands and proposed new areas.