New Idria Road is an approximately 21.5-mile rural highway located in the Diablo Range of San Benito County. From Panoche Road to approximately 20.6 miles to the south the corridor is maintained as the paved San Benito County Road 107. The remaining 0.9 miles to the New Idria ghost town are no longer maintained and have eroded into a high clearance dirt roadway. Upon reaching New Idria the roadway continues south as Clear Creek Road which passes through the Bureau of Land Management owned Clear Creek Management Area.
The New Idria Mercury Mine claim was staked in 1854. Following the theme set by New Almaden the community and mine of New Idria were named after the famous Slovenian mercury mining town of Idrija. Following a slow start the mines of New Idria would boom and the community would reach a peak population of approximately 4,000 by 1880. New Idria Road and Panoche Road were constructed to facilitate stage travel to San Juan Bautista and locales beyond.
New Idria by World War I was largest producer of mercury in the western hemisphere. Following World War II, the demand for mercury would begin to decline. Amid growing environmental concerns over mercury, the mines of New Idria would shutter in 1972. The town never found a buyer who could repurpose the community and mines in a lasting way. In the intervening decades New Idria would decline to a ghost town of increasing obscurity due to being located in a remote corner of the Diablo Range.
New Idria Road in recent years has been subject to numerous washouts. Storms during winter 2021 took out a bridge over Larious Creek. Recovery has been slow as emergency repairs were only completed during September 2024.
Part 1; the history of New Idria
Much of the historic section of this blog was sourced from the excellent BenitoLink article on the New Idria Mining District:
The Environmental Protection Agency compiled summary document regarding the New Idria Superfund Site during November 2014. Said document contains extensive detail about mining operations at the site:
For most of the history of Spanish Las Californias and Mexican Alta California the presence of cinnabar was widely unrecognized by European settlers. Native tribes were aware of cinnabar deposits in the Santa Cruz Mountains near what is now San Jose in addition to those in the Diablo Range at what became the New Idria Mercury Mine.
The first European to discover the Ohlone Cinnabar deposit at Mine Hill (Santa Cruz Mountains) was Secundino Robles in 1824 during the Mexican period of Alta California. Robles not recognizing the significance of his find attempted unsuccessfully to mine for gold and silver with several business partners over the following years.
In 1845 Mexican Army Captain and trained geologist Andreas Castillero proved that the red rocks at Mine Hill contained quicksilver (mercury). Castillero filed a claim during November 1845 with the Mexican Government for the "Santa Clara Mine." The earliest settlement at the Santa Clara Mine was Spanish Town which was plotted in late 1845. In 1846 Castillero sold some of his shares in the Santa Clara Mine to English investors of Barron, Forbes, & Company after being recalled by the Mexican Army due to the Mexican-American War. The new English investors renamed mine to "New Almaden" which was a reference to the Almaden Quicksilver Mine in Spain.
After the Mexican-American War the New Almaden Mine became part of what would become the State of California. The New Almaden Mine spiked in importance due to the onset of the California Gold Rush after the finding Gold at Sutter's Mill was announced to the public. Mercury was an essential product used in the assay process for most of the mines during the California Gold Rush period and would ultimately see the New Almaden Mine become the largest producer in the world.
In 1851 a group of investors raised $9,000 to launch the Aurora Silver Mine at San Carlos Creek near the northwest flank of San Benito Peak in the Diablo Range. The once promising strike turned out be to be a disappointment as what the miners thought to be silver was actually a large seam of chromite. As work continued a large deposit of cinnabar was discovered near the Aurora Silver Mine in 1854.
A claim was filed formally for the New Idria Mercury Mine on March 20, 1854. The additional source of mercury was welcome at the height of the California Gold Rush which led to a boom along San Carlos Creek. The then new boom town was named New Idria in reference to the Slovenian mercury mining town Idrija (then under Austrian control).
The slow start of the New Idria Mercury Mine was referenced in the December 4, 1858, Placer Herald. The article notes production of quicksilver was underway but had yet to be produced in large quantities. The mine owners are noted to be headquartered out of San Francisco. The New Idria Merury Mine had incorporated earlier in 1858.
During the early days of New Idria it was primarily supplied from the nearest major town which was San Juan Bautista seventy-three miles to the northwest. Miners and supply wagons would traverse Panoche Pass through the wilderness of the Diablo Range. The roadway from San Juan Bautista to New Idria would form much of the basis for modern Panoche Road and New Idria Road.
Through much of the early history of New Idria ownership over the mercury claims was highly contentious. At one point there was approximately thirty filed counterclaims over ownership. Many of the counterclaims had basis in existing legislation which had honored Mexican land grants (specifically Rancho Panoche de San Juan y Los Carrisolitos). The matter was finally adjudicated during 1869 by the U.S. Supreme Court case Secretary v. McGarrahan.
In 1869 the United States Post Office would establish service at New Idria. The increasingly prosperous mine would largely spur San Benito County splitting from portions of Monterey County, Merced County and Santa Cruz County on February 12, 1874. By 1880 approximately 4,000 people lived at New Idria which comprised sixty percent of the population of San Benito County.
New Idria can be seen on the 1882 Bancroft's map of California. The mines are shown to be served by New Idria Road which connected to Panoche Road the Southern Pacific Railroad line in Paicines (constructed in 1873). To the south the mines are shown passing through what is now Clear Creek Road towards Fresno Hot Springs (now Coalinga Hot Springs) onward to Warthan Canyon (now California State Route 198). A stage road east from the mine is shown following Arroyo Hondo to Fresno Slough in San Joaquin Valley.
In 1894 the Postal Service would shorten their service name to "Idria." In 1896 the New Idria Quicksilver Mining Company out of Wyoming would purchase New Idria Mercury Mine. By 1900 New Idria surpassed New Almaden as the largest producer of mercury in the western hemisphere. The New Idria mine can be seen below in a 1908 photo from the California State Library.
The New Idria General Store can be seen below in a 1910 era photo (courtesy Western Mining History).
New Idria can be seen at the ends of New Idria Road and Clear Creek Road on the 1915 United States Geological Survey map of Priest Valley. This map does not display the eastern stage route via Arroyo Hondo to San Joaquin Valley. A new road can be seen replacing it via Silver Creek which jogged directly north to Panoche Road.
New Idria can be seen served by New Idria Road and Clear Creek Road on the 1917 California State Automobile Association map. U.S. involvement in World War I saw an increase in demand for mercury products sourced from the mines of New Idria.
New Idria, New Idria Road and Clear Creek Road can be seen in detail in Township 17 South, Range 12 East on the 1920 Denny's pocket map of San Benito County. Clear Creek Road is shown to end at Hernandez which is now the site of a reservoir.
In 1920 and 1923 the New Idria Quicksilver Mining Company went into receivership. The receivers would rebrand as "New Idria Mines Incorporated" in 1923. Through a series of transactions in 1936 the mines of New Idria were purchased by Nevada investors who reverted the name back to New Idria Quicksilver Mining Company.
New Idria Road is displayed as a major local highway (red lines) on the 1935 Division of Highways map of San Benito County. This is one of the last major maps to display an active roadway along Silver Creek.
New Idria can be seen as it was during 1941 (photo sourced from Library of Congress).
In 1951 the New Idria Quicksilver Mining Company would rebrand as "New Idria Mining & Chemical Company." Following World War II there was an increasingly less demand for products utilizing mercury. Mercury was found to have numerous negative health consequences, in particular it was found to be especially dangerous to aquatic life. The 1972 Clean Water Act (enacted October 18, 1972) was largely the final nail in the coffin for major producers in the American mercury industry. The mines of New Idria and New Idria Mining & Chemical Company would shutter production in 1972 due to low demand.
The mines of New Idria produced 44,336,762 pounds of mercury between 1854-1972. Factoring inflation these products would be worth approximately $1.5 trillion U.S. dollars. On January 4, 1974, the Idria Post Office would close.
The auction of the 2,000-acre property of New Idria was announced in the May 12, 1974, Fresno Bee. The auction took place on May 30, 1974, in South San Francisco at the auction house of Wershow Auctioneers. No sale took place, and the New Idria Mining & Chemical Company retained all assets.
In 1976 the New Idria Mining & Chemical Company would convey all properties to EMC Energies and The Hawkins Company. In 1981 the holdings would be merged with what was then called Buckhorn Interim Nevada Incorporated. Buckhorn has had several minor name changes since but still owns the New Idria property.
During 1986 the Futures Foundation would begin a lease of the New Idria property and establish a drug rehabilitation facility at the site. In 1991 Sylvester Herring, the head of the Futures Foundation, personally purchased surface rights lease to New Idria. Between 1991-2006 the Futures Foundation would illegally dump trash at site at the direction of Herring who also owned a trash disposal business. Herring would die during January 2010. During the Herring era there were numerous personal accounts from those passing through the town site being accosted by an unidentified male individual claiming to be armed.
The Environmental Protection Agency would become interested in the uncontrolled mercury runoff from New Idria in 1996. The site was initially assessed during 1998 for inclusion on the National Priorities List, but it was found to not rank high enough. Reassessments were conducted 2003 and 2010.
On July 13, 2010, thirteen abandoned structures in the northern extent of New Idria would be destroyed by fire. The Gilroy Dispatch reported the 24-acre fire destroyed all buildings north of Clear Creek Road aside from the schoolhouse.
This panoramic view of New Idria from Clear Creek Road was taken on May 8, 2009, by Gregg Erikson. Many of the structures in this photo were destroyed in July 2010.
During March 2011 the Environmental Protection Agency would propose adding New Idria to the National Priorities List. The site was found to have unacceptable levels of mercury runoff, asbestos and other mining tailings. Clean up and remediation actions were taken by the agency during 2012-2015. An agreement was reached with Buckhorn Incorporated on December 13, 2018, to study future contamination mitigation.
Time has been unkind to New Idria Road. The highway is maintained as part of San Benito County Road 107 from Panoche Road southeast to Postmile 20.6. The county has vacated responsibility for maintenance for the remaining 0.9 miles to the New Idria town site.
During January 2021 the Larious Creek Bridge on New Idria Road was washed out by heavy storm runoff. The destroyed bridge can be seen in BenitoLink article from March 2021.
A temporary ford of Larious Creek was constructed after the storms of winter 2021 to permit access to homeowners and ranchers along New Idria Road. These repairs were intended to be temporary, and San Benito County placed a "road closed to through traffic" sign at the beginning of New Idria Road branching south from Panoche Road. Effectively the only legal way to enter New Idria was to obtain a permit from the Bureau of Land Management to drive to the town via Clear Creek Road in the Clear Creek Management Area.
During September 2024 emergency repairs were made to New Idria Road. The first eight miles of the roadway south of Panoche Road were resealed. An earthen culvert was installed along with a drainage pipe at Larious Creek. Following these repairs New Idria Road was fully reopened to public use.
San Benito County intends to replace the Larious Creek Bridge. The county requested a California Environmental Quality Act exception to move forward with construction of a new 95-foot span on March 4, 2025. The destroyed Larious Creek Bridge is noted to have been constructed at some point between 1947 and 1958.
Former New Idria resident Kate Woods was featured in several YouTube interviews about what life was like in the community (courtesy Wanda Guibert of the San Juan Bautista Historical Society):
Kate Woods would be involved in a fatal car crash on New Idria on July 25, 2017. She was a highly respected San Benito County environmental activist and journalist:
Southbound New Idria Road begins at wye along eastbound Panoche Road.
Southbound New Idria Road passes by a parking area for the Griswold Hills Day Use Area.
New Idria Road continues southward through a canyon following Griswold Creek. The roadway to approximately Postmile 7.8 is comprised of the asphalt surfacing applied in September 2024.
The asphalt surface on New Idria Road degrades heavily upon entering a valley known as Vallecitos (Spanish for Little Valley).
New Idria Road crosses the recently filled in site of the Larious Creek Bridge.
New Idria Road picks up the course of San Carlos Creek and begins an ascent to New Idria. The roadway passes by an old adobe at what was Jones Ranch.
San Benito County maintenance of New Idria Road terminates at Postmile 20.6. Traffic is greeted with a sign which reads "THIS ROAD IS NOT MAINTAINED, SAN BENITO COUNTY IS NOT RESPONSIBLE FOR LOSS OR INJURY SUFFERED BY REASON OF IT'S USE."
The remaining 0.9 miles of New Idira Road is a heavily eroded mix of asphalt and ungraded dirt. As the roadway reaches New Idria it becomes Clear Creek Road. Traffic arriving in New Idria is greeted with a sign welcoming them to the historic mines.
New piping has been at the mine tailing pond which redirects water flow of San Carlos Creek under the roadway. Previously the water would spill over the road entering New Idria. The tailing pond and most of the major mine buildings are blocked via mostly new fencing.
The tailing pond from the view of a drone.
The structure which houses the three rotary kilns for mercury ore refinement is rough condition. The roof has collapsed on this structure in the past decade.
Drone photography reveals the extent of the roof collapse.
A couple more drone photos of the wreckage behind the fence line.
These homes and other facilities flank south of Clear Creek Road. As noted in Part 1 thirteen the structures on the opposite side of the roadway were destroyed in the 2010 fire.
Several of the remaining structures in New Idria can be seen from Clear Creek Road as it winds above the community towards the Clear Creek Management Area boundary.
A final series of views of the ruins of New Idria before returning to northbound New Idria Road.
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