Bonds Flat Road

Bonds Flat Road is an approximately six-mile highway in the Sierra Nevada foothills of Tuolumne County near La Grange. The roadway crosses New Don Pedro Dam and was opened to traffic in 1971 following completion of said structure. The corridor begins at La Grange Road (County Route J59) and terminates at California State Route 132.

Part 1; the history of Bonds Flat Road

Bonds Flat Road was constructed as part of the New Don Pedro Dam project. The roadway is one of the pieces of nearby infrastructure not named after the famed California Gold Rush figure Don Pedro Sainevain. An undated public domain photo of Sainsevain can be seen below.

Sainsevain was born on November 20, 1818, in Béguey, France. He would arrive in Santa Barbara of then Mexican Alta California during July 1839. Sainsevian was a carpenter by trade and was sent to find his uncle in Los Angeles. He would initially settle near downtown Los Angeles where he became a prominent figure in the coastal wine industry.

Through the 1840s Sainsevain would diversify his business interests by way of becoming involved sawmills, flour mills, ship building and mining. In 1848 would visit Coloma in the buildup to the larger California Gold Rush and would establish Don Pedro Bar on the banks of the Tuolumne River. In 1849 Sainsevain would soon divest of his mining interests and would move to Stockton where he found a profitable business selling wine to Gold Rush miners.

Sainsevian would be later involved in the construction of California's first State House and was a delegate at the California Constitutional Convention in Monterey. He would remain successful in the California wine industry until leaving the state for France in 1883 following the death of his wife. Sainsevain would die in France on October 4, 1904.

Don Pedro Bar can be seen along the Tuolumne River northeast of La Grange on the 1873 Bancroft's map of California. The original Don Pedro Road is shown along both sides of the Tuolumne River.

The site of Don Pedro Bar can be seen on the 1893 United States Geological Survey map of Sonora. Don Pedro Road is shown to cross the Tuolumne River and connect to what is now Granite Springs Road.

The site of Don Pedro Bar would later be submerged during construction of Don Pedro Dam. The original arch concrete dam was built near the town site along the Tuolumne River by the Modesto Irrigation District. The dam was complete by 1924 and is 283 feet high.

The original Don Pedro Dam can be seen in a 1925 era public domain photo.

The 1935 Division of Highways map of Tuolumne County displays the completed Don Pedro Reservoir. The dam site is shown to be accessible via road branching east from La Grange Road to Buzzards Point (now called Don Pedro Road on modern maps).

In 1961 bonds were issued to expand the existing Don Pedro Reservoir. The expansion required a new dam to be constructed downstream from the existing arch concrete structures. After delays construction of the New Don Pedro Dam would commence with the spillways on August 29, 1967. The new dam was an embankment design which topped out on May 28, 1970. Old Don Pedro Dam was covered by rising waters on April 12, 1970.

New Don Pedro Dam would be completed and dedicated in 1971. The structure is 585 feet high and has length of 1,900 feet. The embankment dam shas an installed 203-Megawatt Capacity. Bonds Flat Road was constructed as an access road to the then new structure. The roadway also served as a cutoff from La Grange Road (County Route J59) to California State Route 132.