Surface water consists of rainfall and runoff in creeks and lakes from a tributary area, which is called a watershed. Two distinct watershed regions supply the surface water resources for Stanford. The San Francisquito Creek watershed is located in the northwest part of campus. Runoff from the Stanford campus area of this watershed is conveyed through large pipelines all the way to San Francisquito Creek, just south of El Camino Real. The Matadero Creek watershed is in the southeast part of campus, and its runoff is conveyed to a large Caltrans storm drain along El Camino Real, which then conveys storm water to Matadero Creek.
Surface water is the main source for the campus lake (non-potable irrigation) water system which is used to irrigate the majority of the campus; groundwater is used to supplement surface water supplies during dry years.