Hydraulics were used to widen and strengthen the dam, with workmen shoveling and spraying earth from nearby hills into a metal-lined wooden flume so gravity could move it to the dam, as shown in an 1888 sketch by John Muir, and a superintendent’s cottage once stood on top of the hill. Underneath the mock neo-classical temple lies the inlet of Tunnel No. 2, completed in 1875 and connected to the main Oakland pipelines in 1876, while the decorative temple, called Diana’s Temple, was built in 1917. Tunnel No. 3 was built in 1889 as a secondary spillway to carry excess water from the reservoir back to San Leandro Creek, and it was dug and dynamited 1,438 feet through rock to an exit visible near the city of San Leandro’s Chabot Park.