Up Blair Avenue: Geology, Water Wars, and a Forgotten Reservoir

Our Piedmont Recreation Department’s Walking on Wednesdays group had another cool, mild, mid-winter morning for its walk last Wednesday. There was an excellent turnout of 47 walkers and four K-9 best friends at the Exedra for a challenging uphill climb to one of Piedmont’s least understood structures, the EBMUD “Reservoir Number Two,” near the top of Blair Avenue.

Two years ago, Karin F and Peggy S told the group about Deep Oakland, a book by Andrews Alden. In it, Alden tells how geology has shaped Oakland and the East Bay and he includes a chapter on Piedmont. He also explains why the Piedmont Reservoir is up at the top of Blair. Meghan Bennett’s History of Piedmont website, https://www.historyofpiedmont.com/, also provides historical information about the reservoir and photos. We last went to the reservoir in 2024 and it was time for another visit.

Alden wrote there is a separate block of the Earth’s crust, west of the Hayward Fault on a set of rocky hills, measuring about four by two miles. It’s called the “Piedmont block.” No other East Bay city has anything like it. It reaches half the elevation of the high Oakland Hills and neatly encloses the city of Piedmont. The block’s eastern border is the Hayward Fault, running along the Montclair district.

Oakland was incorporated in 1852 in the wake of the State's growing population because of the California gold rush. It was near the Bay and an oak forest growing on ancient sand dunes. The natural landing at the foot of Broadway needed reinforcement with large boulders to make a sturdy shore. The city’s loose ground, stripped of trees, made for streets that were sticky in the rain and dusty in the sun and the city managers decided to pave the streets in the 1860s with lots of crushed stone.

The Piedmont block contains a variety of rock types, but all of them belong to the Franciscan Complex, a great body of mixed rocks found up and down the Coast Range. The earth below the Piedmont block is mostly a hard, thick-bedded sandstone. It was extracted from many stone quarries in the area during the second half of the 19^th Century and early 20^th Century and was used to pave the area’s streets.

The landscape in the Piedmont block is different from that of the high hills east of the fault. The slopes are gentler and more rounded. The high rocky rims on the eastern edge serve as a watershed that naturally collects water as the Oakland hills do. Their elevation and upward slope cause the moisture in Bay breezes to rise, cool, and condense as fog and rain. The Piedmont block naturally collects more rainfall than the plains around it, and there is enough water to support five permanent creeks that come together at Lake Merritt.

We headed off going up Highland, Sierra, Sheridan and Lakeview Avenues, and then up Poplar Way. We emerged on Mountain and started our climb up the lovely, but steep Bellevue, Pacific, and Hager Avenues to get to Blair. Just down the street was the fenced reservoir. We stopped in front of it for its story to be told and a group photo to be taken.

Water for the first, small East Bay towns came from household wells. The best places became wellfields, owned by small providers of what they called “pure, fresh water.” Later, there was a need for bigger wells, and they were found in the lowlands near the Bay. Some are still active today. Private companies soon offered more dependable water at low cost. As the East Bay grew, these water companies competed for customers and those on the high ground had an advantage. Their tanks and reservoirs could use gravity to supply pressure and regulate the flow independent of the weather.

William Dingee was born in Pennsylvania in 1854 and came to Oakland in 1877. He worked first as a bookkeeper and did well in real estate. In 1891 he had plans for a water district to serve fine Piedmont homes. He applied for a supply of water from the Contra Costa Water Company (CCWC) but was turned down because they were unable to meet his needs. Undeterred, Dingee went ahead on his own and within a few months had bored the first of 22 tunnels to tap groundwater from springs in the high, uninhabited Oakland hills directly to the east.

Tunnels in high ground are a poor source of water, but it could be piped downhill to a reservoir without pumps. This limited, but cheap supply was enough to get Dingee started. Within two years he was running the Piedmont Springs and Water Company. He piped his water from Moraga Peak to a reservoir in Piedmont and later incorporated his operation as the Oakland Water Company. The Piedmont Reservoir held the water from Dingee’s tunnels, and its elevation provided good water pressure for the neighborhoods below. This reservoir was an open basin that got a lid of concrete and steel 60 years later.

Dingee quickly became the CCWC's biggest competitor. The competition became heated and both companies were reported to have worked to disrupt the other’s supply, and a price war ensued. At the turn-of the-century, after a protracted battle, the two companies merged. The new company was known as the CCWC, but Dingee was at its helm. 

However, the new CCWC lasted only until 1906. The Peoples Water Company, whose president was Frank C. Havens, was created and it took control of CCWC and other local water companies. Dingee's fortunes collapsed in about 1908. One report said he was swindled by a business partner. Following the collapse of his financial empire and subsequent bankruptcy, Dingee lived out his years in obscurity in Sacramento and died in 1941 at the age of 87.

Peoples Water immediately also faced challenges as the demand for water increased substantially in the early years of the 20th century. Ten years later, in 1916, the East Bay Water Company was incorporated and took over Peoples Water. But East Bay Water had problems too. Not only was demand from household consumers increasing, but World War I significantly increased the need for water by local industry.

By 1919, ten reservoirs throughout the East Bay, including those in Piedmont, were being operated by the East Bay Water for either filtration or sterilization. It tried to satisfy its customers, but public opinion shifted in favor of public ownership of water management and distribution. In 1921, the State legislature approved a bill that provided for the creation of a municipal utility district. That district, EBMUD, was approved by voters in 1923.

The EBMUD “Reservoir Number Two” occupies more than nine acres straddling the Oakland-Piedmont border with 8.3 acres in Piedmont. Two other reservoirs of this type and vintage sit higher on the ridge in west Montclair. One is on Bullard Drive named for Dingee, and the other on Estates Drive is named “Reservoir Number One.”

Reservoir Number Two’s 22.8 million gallon water storage tank provided water for Piedmont from 1905 to 2003. The facility was decommissioned and drained in 2003 as part of an EBMUD’s facility modernization program. It was also an earthquake flood risk. Piedmont’s water now comes from other large tanks in the Oakland hills.

The walkers asked why the reservoir’s site wasn’t being put to use now. Former Piedmont Planning Commissioner Jim Kellogg explained the issue had been raised. The land has a steep grade, and construction would be very expensive. Neighbors might have issues too. Additionally, the land is in Oakland and Piedmont and owned by EBMUD. Getting an agreement between the parties was not realistic and the Piedmont Reservoir became an unused Piedmont landmark.

After all this information and history, we enjoyed a direct downhill return to the Exedra via Blair, Pacific, and Dormidera Avenues with a better understanding of how Piedmont’s geology, water, and history are connected.

P.S. Lori Rubens asked that I share with you that the Jewish Family Community Services East Bay will be having its 19th annual Art of Living Gala on April 19, 2026 at 5:30pm at Bloc15 in Jack London Square, Oakland. The link for it is https://jfcs-eastbay.org/AOL26/