The reservoir was originally formed in 1926 when the first San Leandro Dam was completed, and it was first filled by the Mokelumne Aqueduct in 1929.

[4] It inundated a long section of the San Leandro Creek valley, including the towns of Valle Vista and Redwood.

The original dam was constructed between 1924 and 1926 using the hydraulic fill method and was considered seismically inadequate.

[2] Tributaries that flow into the lake include San Leandro, Moraga, King Canyon, Kaiser, Buckhorn and Redwood Creeks.

[7] The reservoir and its feeder streams have a population of landlocked rainbow trout whose migration to San Francisco Bay was blocked by the dam.