Orestimba Creek, originally Arroyo de Orestimba (Orestimba, a Yokutsan word for "meeting place") is a tributary of the San Joaquin River draining eastern slopes of part of the Diablo Range within the San Joaquin Valley of California.
History The Orestimba name derives from the Ohlone language ores meaning bear. It is first mentioned as Arroyo de Orestimac in the historic record in Padre José Viader's exploration diary of 1810. He was the long-serving head of Mission Santa Clara de Asis. Arroyo Orestimba was a watering place on El Camino Viejo in the San Joaquin Valley and was the primary water source for Rancho Orestimba y Las Garzas near its northern boundary. Diseño del Rancho Orestimba The ranch house of Rancho Orestimba y las Garzas, was built above the sycamore grove on Arroyo de Orestimba. Mildred Brooke Hoover, Douglas E. Kyle, Historic Spots in California, Stanford University Press, 2002, p.517
In 1981 the Mustang-Gill Ranch, which included much of the South Fork Orestimba Creek watershed in southwest Stanislaus County, was acquired by California State Parks and became part of Henry W. Coe State Park. The Park's General Plan, approved in 1985, designated the of the Park as the Orestimba Wilderness.
In 1998 the Simon Newman Ranch was acquired by The Nature Conservancy which continues to manage its which include the eastern Diablo Range foothills watersheds of both Orestimba Creek and Garzas Creek.
Watershed and Course The Orestimba Creek watershed drains and is the largest of the 13 tributaries of the San Joaquin River's westside basin.
The Orestimba Creek mainstem has its source at the confluence of the North Fork and South Fork of Orestimba Creek (elevation ) and flows northeast to its mouth at the San Joaquin River north of Newman in Stanislaus County.U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map , accessed June 7, 2026 Its two major tributaries each begin just west of the Diablo Range Crest just inside Stanislaus County's border with Santa Clara County. North Fork Orestimba Creek begins at elevation about north-by-northwest of Black Mountain and the much longer and lower gradient South Fork Orestimba Creek begins at elevation .
After the confluence of the North and South Forks, mainstem Orestimba Creek receives only two named tributaries (from the left heading downstream): Oso Creek in the mountains and Crow Creek on the Central Valley floor. North Fork Orestimba Creek receives no named tributaries. However, South Fork Orestimba Creek receives several named tributaries, all beginning just west of the Diablo Range Crest and joining from the left: first Hartman Creek, then Red Creek, then Robison Creek, and then Sheep Thief Creek.
Ecology The Orestimba Creek watershed is dominated by blue oak (Quercus douglasii) and gray pine (Pinus sabiniana) with patches of riparian, chaparral and grasslands habitats. Native mammal species include black-tailed jackrabbit (Lepus californicus), brush rabbit (Sylvilagus bachmani), California ground squirrel (Otospermophilus beecheyi), coyote (Canis latrans), grey fox (Urocyon cinereoargenteus), striped skunk (Mephitis mephitis), bobcat (Lynx rufus), puma (Puma concolor) and Columbian black-tailed deer (Odocoileus hemionus columbianus). Historically pronghorn (Antilocapra americana) and tule elk (Cervus canadensis nannodes) were present, with tule elk now present after translocations to Mount Hamilton circa 1980.
Recreation Upper South Fork Orestimba Creek and its Hartman Creek, Red Creek and Robison Creek subtributaries are included in a designated wilderness area of about in a northern section of Henry W. Coe State Park known as the "Orestimba Wilderness".
References
External links Henry W. Coe State Park California Water Indicators Portal: Orestimba Creek watershed