The site of Yema-po was discovered in 1980 when a construction crew, rebuilding the spillway of the Lake Chabot Dam in San Leandro, accidentally bulldozed the edge of a historic work camp. The camp had been used by the original Chinese laborers who had built the Lake Chabot Dam over a hundred years before. Controlled excavations of the site, officially known as CA-Ala-423H, were conducted by faculty and students from the Department of Anthropology, California State University, East Bay in 1980, 1981 and again in 1994.
The site is located just to the south of San Leandro Creek downstream from the spillway of the Lake Chabot Dam. Chinese and Euro-American artifacts were found in an area measuring approximately 25 meters by 20 meters on and below an old river terrace of San Leandro Creek. Excavation on the terrace surface revealed a shallow deposit of highly fragmented Chinese artifacts, metal construction materials and animal bones.
On the slope below the terrace a much deeper deposit of materials was found. The artifacts and ecofacts found in the lower slope excavations were much the same as those found on the terrace, but much less fragmented, having been protected by as much as 80 centimeters of soil. The lower deposit probably represents a convenient dumping ground for the Chinese workmen who were living on the terrace above.
A total of 16 one meter by one meter excavation units were dug on both the terrace and the lower slope during the summer of 1980. In the spring of 1981, because the lower slope had been destroyed by vandals armed with a backhoe sometime in the interim, units were opened only on the terrace. During the spring of 1994 several additional units were excavated on the terrace.
Very little evidence of any architectural remains that might represent structures used by the Chinese workers of Yema-po was found either on the terrace or the lower slope. The only exception to this statement was found on the edge of the terrace and appears to represent the partial remains of a brick-lined hearth which consisted of a concentration of mortared bricks, rocks, iron hardware and thermally altered soil.
This feature, along with the discovery nearby of fragments from a large iron wok and the abundance of food-related materials from all parts of the site, suggest that the terrace was the original living surface of the Chinese workers camped at Yema-po. The hearth feature, although still somewhat enigmatic, probably represents the remains of an outdoor cooking stove over which communal meals were prepared. Based on the lack of other architectural features and the camp model known best for the overseas Chinese that worked on the transcontinental railroad, we suspect that the Yema-po laborers lived in a tent-cabin situation like that illustrated below.