Permanente Creek covers an area of approximately 17.5 square miles on the northeast-facing slopes of the Santa Cruz Mountains. The headwaters originate near Black Mountain along the Montebello Ridge. Permanente Creek flows east through unincorporated County land for about five miles, then turns to the north at the base of the foothills and continues another eight miles along the valley floor traversing through the cities of Los Altos and Mountain View, finally draining to the Lower South San Francisco Bay. The major tributaries are the West Branch Permanente Creek and Hale Creek.
Unlike most watersheds in the Santa Clara Basin, the headwaters of the Permanente Creek are not protected as open space, but are developed for light industry and mining. Only the headwaters of the West Branch Permanente Creek are protected as open space by the Mid Peninsula Open Space District. The majority of the watershed downstream of this tributary confluence is developed as high-density residential neighborhoods, with commercial development clustered along major surface streets such as El Camino Real. Some heavy industry is clustered adjacent to Highway 101 in the lower watershed by the Bay.
Four species of native fishes have been collected and/or observed from Permanente Creek during the last 20 years: rainbow trout, California roach, Sacramento sucker, and threespine stickleback. The native fish assemblage primarily occurs in the reaches upstream of Interstate 280.
- Watershed area: 17.3 square miles
- Number of tributary creeks: 7
- Miles of natural creek bed:
- Miles of Engineered Channel:
- Local towns and cities: Santa Clara County, Palo Alto, Los Altos, Mountain View
- Percent area by land use:
- Residential 46.3%
- Industrial/Commercial 13.1%
- Forest 35.0%
- Rangeland 2.8%
- Other 2.8%
- Percent Impervious Area: 43.9%
- Beneficial Uses: Cold Freshwater Habitat (COLD), Fish Spawning (SPWN), Wildlife Habitat (WILD), Water Contact Recreation (REC-1), Noncontact Water Recreation (REC-2)
- Water Quality Impairments: Urban Pesticide Toxicity (Diazinon), Selenium, Toxicity, Trash