Human Impact on Jasper Ridge Biological Preserve

Extracts from chapters 14 and 15 of JRBP Bio 96 A/B Docent Training Class Handbook, 2005 ed.

Hunting, Gathering, and Fires

Hunting, gathering, and fires set by Indians were the first human impacts on the Preserve. Throughout California, native peoples used fire to encourage the spread of grassland and woodland habitats that supported useful plant and animal species. For at least 5,000 years, Indian occupants of the San Francisquito area probably were setting fire to small patches of the local landscape, including Jasper Ridge. It is likely that the distribution of grassland and woodland observed by the Spanish in the late 1700s resulted at least in part from Indian activity.

Cattle Grazing

Cattle grazing, in the general area of Jasper Ridge, began soon after the Spanish established Mission Dolores in 1776 and Mission Santa Clara in 1777; although careful Spanish attention to branding and herding suggests that no cattle may have reached the relatively inaccessible upper Jasper Ridge grasslands until after Mexican independence in 1821. In 1854, a property line was established, now marked by the Westridge fence, and modern aerial photos show that the grassland along Escobar road was artificially cleared. Cattle grazing continued until April 1960, when cattle were removed permanently from the upper grassland because of Ehrlich’s study of the Bay Checkerspot butterfly. The SLAC corridor was maintained as a grazed grassland in the Preserve. In 1979, grazing was terminated in the SLAC corridor as well, to facilitate Professor David Regnery’s ground squirrel study.

Logging and Other Wood Cutting

Logging and other woodcutting also may have begun on Jasper Ridge soon after 1777. Certainly it began then in nearby areas. The 1834 and 1844 land grants covering Jasper Ridge were called “Canada del Corte de Madera” and “Rancho del Corte de Madera”, the place for cutting wood. The 1849 Gold Rush made San Francisco an instant city and created heavy demand for lumber and redwood shingles: the first local sawmill was built on Alambique Creek in 1849, by Charles Brown, and in 1852 Dennis Martin built two sawmills on the creek that now bears his name. Whenever they were cut, the very accessible Jasper Ridge virgin redwoods must have been among the first of their kind to go. Many of their stumps still can be seen along the creek, most having stumpsprouted into rings of second-growth trees.

The blue oak woodland on the northwest slope of Jasper Ridge has some trees that stump-sprouted, probably in the last quarter of the nineteenth century. These equal-aged trees may have resulted from clear cutting, another possibility is that the trees were cut for fuel during the Searsville Dam construction project. However, a few older trees in the woodland, remnant toyon and chamise east of the woodland, suggest that this area may once have been mixed chaparral.

Cattle browse on oak seedlings, and trample acorns. Continuously grazed grasslands on and about the Preserve now display only ancient oaks, which have been inhibited from reproducing by cattle. Deer also browse oak seedlings and eat acorns. In less heavily grazed areas in the state, there are stands of late nineteenth century oaks that correlate with the historic decreases in deer population. Perhaps the equal aged blue oaks result from a time of low grazing by cattle, deer, or both.

The Town of Searsville

The town of Searsville, which existed for only 35 years, was established near the Corte Madera drainage, close to the footbridge that now leads to Trail 13. In 1850, Dennis Martin bought this land, and along with others built sawmills on the adjacent creeks. Soon bunkhouses, a blacksmith shop, and private houses were constructed. In 1854, John Sears built a house near the present junction of Portola and Old La Honda roads and a school was built on the knoll above the settlement. When a newspaper printed a story about “Searsville” the name stuck. The town grew and then declined relative to logging in the area. In its heyday, Searsville contained a hotel, a store, a post office, a blacksmith shop, a lumberyard, assorted homes, the school, and gambling houses and saloons. In 1862, Sears himself followed lumbermen over Skyline to the La Honda area. For the next five or six years, various residents participated in a short-lived mining boom. In 1866, a subdivision map was filed showing a grid of streets and 63 small lots in the meadow. Then in 1879, the U.S. District Court condemned Searsville land for a projected reservoir. The Searsville residents sold their property, and, as was common in those days, moved the buildings and almost all of the building materials to new sites. Despite legend to the contrary, there are no buildings underwater in Searsville Lake.

Searsville Dam

Searsville Dam construction began in 1888, and was completed by November, 1891. The dam was 50 feet broad at the base, 14 feet broad at the top, and 60 feet high, with no provision for lake level control below that height. In 1919, the narrow crown that is the walkway over the dam was added to raise maximum water level by 7.5 feet. The crown construction included removable weir boards that allowed for the adjustment of the water level within a 4.5 foot range.

Searsville Dam survived the 1906 and the 1989 earthquakes with only minor damage because of its design. The dam’s individual concrete blocks interlock and this permits enough movement to dissipate the shock. The Crystal Springs and San Andreas dams are of similar construction. The Searsville dam is inspected regularly by the State of California and Stanford University.

Originally, Searsville Lake was intended to be part of a chain of reservoirs, including the San Andreas and Crystal Springs, that were built by the Spring Valley Water Works (SVWW), to collect domestic water for sale to the city of San Francisco. However, by the time the Searsville dam was completed, the water was directed to Stanford University.

Spring Valley did not originally plan for the water to benefit Stanford in this way. The town of Searsville’s condemnation in 1879, presumed the extension of the San Francisco water service, and in 1886, the company surveyed for a large tunnel to connect Searsville and Crystal Springs reservoirs.

This plan changed because of prior events. In the early 1880s, Leland Stanford acquired land on the eastern side of the projected lake’s headwaters; and in 1885, he established a university. In 1886, Stanford created a separate water company to serve the university, along with rights to build a dam downstream on San Francisquito Creek between what is now called Rattlesnake Rock and the junction with Los Trancos Creek. Stanford was both the owner of the water company holding specific runoff rights as well as a hard man to argue against in court. As a result, he had Spring Valley in a difficult situation with only two choices: either accommodate Stanford’s interests or abandon Searsville Dam.

In 1887, Spring Valley signed a contract with Stanford which stipulated that: (a) SVWW would build and operate a dam at least 60 feet above the bed of Corte Madera Creek; that construction would be completed by November 1890 (later extended to November 1891) and that SVWW would draw no water from lower than 60 feet above the creek bed. Plus, (b) Stanford would give SVWW upstream land rights to impound such a reservoir, and that the university would draw no more water than could pass through a pipe 12 inches in diameter and one mile long. This pipe is still visible in areas.

Spring Valley apparently speculated that it could acquire enough land upstream to allow a higher impoundment, which would reimburse the entire project; their proposed dam rose 100 feet above the creek. SVWW lost in this speculation and had to build the Searsville dam to meet its contractual obligations. After the 1906 earthquake, Stanford University took over the operation of the dam. In 1916, the university acquired title to dam, lake, and the hillside immediately east of the dam.

The Searsville Laboratory

The Searsville Laboratory is a reminder that for 55 years Searsville Lake was the main attraction of a public recreation area. Prior to the construction of the Sun Field Station, Searsville Lab housed the office of the Jasper Ridge scientitfic coordinator, the herbarium collection, and provided a small indoor work area for researchers. During the recreational era of Searsville Lake, the building was used primarily as a snack bar. A cement block bathhouse was located near Searsville Lab, but was removed in 2003.

Searsville Lake Park

Searsville Lake Park began in 1922, when Ernie Bransten, the Stanford swim coach, leased the rights to the lake and the hillside east of Searsville Lake from the university. Park visitors entered near the Whiskey Hill Gate, and crossed San Francisquito Creek on a bridge (the concrete footings are still visible at the cement crossing). They paid a fee at tent cabins set up under oaks in the meadow (the cabin footings also still there), parked in the horseshoe curve below the dam, and walked up and along the lakeside trail to reach dressing rooms by the live oaks on the hill opposite our present boat dock.

Meanwhile, the Spring Valley Water Company retained its land west of the lake, and was planning a development called “Lakeshore Hills” which would have put 129 houses between Searsville Lake and Sand Hill Road. Although this plan was approved by San Mateo County in 1924, the development was never constructed and Stanford University subsequently acquired the property.

In 1927, Bransten expanded Searsville Park to surround the lake and moved the main entrance to the corner of Sand Hill and Portola roads. Branston imported sand from Santa Cruz County for a beach, built a snack bar, a house, and a high-diving tower on the dam (the metal base still there). In 1929, the university built the causeway to divert sedimentation and Bransten constructed the fire road to create a loop that connected the hillside with the original tent cabin site, then returned to cross San Francisquito Creek below the dam. Several picnic areas were located along this drive and historical evidence of this era is abundant.

Bransten ran the park for 33 years, until 1955, when Austin Clapp took over. Clapp built the bathhouse (occasionally rented to Stanford fraternities for parties), and the bike bowl (never was used for bicycle racing), and planted the Douglas fir trees on the hill above the Sun Field Station. Clapp and his family ran the park for 18 years.

By the late 1960s, economic and social problems forced Stanford to reexamine the park’s lease at the same time that the university was assessing the needs of the Jasper Ridge biological study area. The Department of Biological Sciences was given control over the lake and parkland and hired a management consultant for advise on how to run a public park in conjunction with Jasper Ridge. In 1973, based on the consultant’s advice and the formal designation of the Jasper Ridge Biological Preserve, Stanford negotiated a restrictive park lease solely on land west of the lake. From the Preserve standpoint, the next four park seasons were disastrous. Addison Janes, the new leaseholder, had to deal with rowdy crowds and visitor volume that was significantly higher than the park could accommodate or control. Vandalism in the Preserve increased as well as in the surrounding communities. The Town of Woodside and San Mateo County threatened legal action.

In 1976, Stanford took advantage of a timely bequest to buy out the park lease and add its holdings to the Jasper Ridge Biological Preserve. A fence was built along Sand Hill Road, and the former snack bar was renovated into the Searsville Lab. A bridge built at Bransten’s crossing below the dam connected both halves of the expanded Preserve and the causeway bridge was rebuilt. The Searsville area became the hub of the academic activity in the Preserve.

The Stanford Linear Accelerator Corridor (SLAC)

The SLAC Corridor is a strip of land between San Francisquito Creek and the SLAC chain link fence. The corridor was part of the original SLAC lease from Stanford, but control over it became essential for effective management of the Jasper Ridge Biological Preserve. The corridor has been managed by the Preserve since 1973, and was formally included in the Preserve in 1976.

The SLAC Power Line

The SLAC power line provides electricity to the Stanford Linear Accelerator Center. The line carries 230,000 volts: the accelerator, when turned on, uses 26,000,000 watts, and the SLAC facility uses another 12,000,000 watts. The SLAC line was built in 1963–64 to connect with PG&E’s main transmission line in the hills. It is owned by PG&E, but power for SLAC is provided by the federal government from Pacific northwest hydroelectric projects. The SLAC lines within the Jasper Ridge Biological Preserve cut across above Rattlesnake Rock and were approved by Stanford biologists. The location and type of the power lines for SLAC were the subject of intense local controversy in the early 1960s. During this debate former Congressman Pete McCloskey first gained prominence. A low visual impact green power pole was designed; these poles were installed by helicopter to minimize ecosystem disturbance.


Bocek, Barbara and Elena Reese. 1992. Land Use History of Jasper Ridge Biological Preserve, Research Report No. 8.
Bocek, B. 1986. Hunter-Gatherer Ecology and Settlement Mobility along San Francisquito Creek. Ph.D. Thesis, Anthropology, Stanford University.
Regnery, D. 1991 The History of Jasper Ridge: From Searsville Pioneers to Stanford Scientists. Stanford Historical Society, Stanford, CA.