1888 map showing the Eagle Rock Creek winding Westward through the Yosemite valley. (California State Archives)
A six foot diameter pipe is lowered into a trench under Yosemite Drive, 1936. (ERVHS)
Workers digging a stormdrain in 1937 on Neola Street near Glacier Drive. (ERVHS)
The southern end of Eagle Rock Valley, roughly the location of present day Yosemite Drive, was once a collecting point for water from Eagle Rock Creek as well as from the foothill streams.
With increased settlement and lowering of the water table, this stream was barely evident by the 1920s, except during rainy season. Bob Cota remembers the rest of the year there were only spotted pools along the shallow bed. But when water flowed, people would dig along the side of the streambed and would haul away water for domestic purposes.
A tunnel was necessary to convey the water from Yosemite Drive across the Eagle Rock Boulevard, toward Ellenwood Drive, where it continued on its way to the Los Angeles River.
Before the 1923 annexation of Eagle Rock to Los Angeles, Yosemite Drive was called "Sycamore Avenue". The California sycamore is associated with floodplains and intermittent streams--it thrives where its roots have access to water.