The Guadalupe River mainstem is an urban, northward flowing 14 miles (23 km) river in California whose much longer headwater creeks originate in the Santa Cruz Mountains. The river mainstem now begins on the Santa Clara Valley floor when Los Alamitos Creek exits Lake Almaden and joins Guadalupe Creek just downstream of Coleman Road in San Jose, California. From here it flows north through San Jose, where it receives Los Gatos Creek, a major tributary. The Guadalupe River serves as the eastern boundary of the City of Santa Clara and the western boundary of Alviso, and after coursing through San José, it empties into south San Francisco Bay at the Alviso Slough.

The Ohlone, formerly known as Costanoans, are a Native American people of the Northern California coast. When Spanish explorers and missionaries arrived in the late 18th century, the Ohlone inhabited the area along the coast from San Francisco Bay through Monterey Bay to the lower Salinas Valley. At that time they spoke a variety of related languages. The Ohlone languages make up a sub-family of the Utian language family. Older proposals place Utian within the Penutian language phylum, while newer proposals group it as Yok-Utian.