San Francisco Peninsula, in the northwest part of the Santa Clara Valley (Silicon Valley) approximately southeast of San Francisco and approximately northwest of San Jose. $4.5 billion was received by Stanford in 2006 and spent more than $2.1 billion in 2 counties named Santa Clara, and San Mateo. In 2008, 60% of this land remained undeveloped. Stanford's main campus includes a census-designated place within unincorporated Santa Clara County, although some of the university land (such as the Stanford Shopping Center and the Stanford Research Park) is within the city limits of Palo Alto. The campus also includes much land in unincorporated San Mateo County (including the SLAC National Accelerator Laboratory and the Jasper Ridge Biological Preserve), as well as in the city limits of Menlo Park (Stanford Hills neighborhood), Woodside, and Portola Valley. The central campus includes a seasonal lake (Lake Lagunita, actually an irrigation reservoir), home to the vulnerable California tiger salamander. As of 2012 Lake Lagunita was often dry and the university had no plans to artificially fill it. Two other reservoirs, Searsville Lake on San Francisquito Creek and Felt Lake, are on more remote sections of the founding grant. Central campus The central academic campus is adjacent to Palo Alto, bounded by El Camino Real, Stanford Avenue, Jane Stanford Way, and Sand Hill Road. The United States Postal Service has assigned it two ZIP Codes: 94305 for campus mail and 94309 for P.O. box mail. It lies within area code 650. Non-central campus Stanford currently operates in various locations outside of its central campus. On the founding grant: Jasper Ridge Biological Preserve is a natural reserve south of the central campus owned by the university and used by wildlife biologists for research. Researchers and students are involved in biological research. Professors can teach the importance of biological research to the biological community. The primary goal is to understand the system of the natural Earth. SLAC National Accelerator Laboratory is a facility west of the central campus operated by the university for the Department of Energy. It contains the longest linear particle accelerator in the world, on of land. Off the founding grant: Hopkins Marine Station, in Pacific Grove, California, is a marine biology research center owned by the university since 1892. Based on US Pacific Coast, it is one of the oldest marine laboratories. It includes 10 research laboratories and is also used for archaeological exploration purposes.