Orestimba Creek is an ephemeral stream in a small agricultural basin within the valley floor on the west side of the San Joaquin Basin. Streamflow results from storm runoff in the winter, and irrigation return flows in the spring and summer. During the winter, the creek can also received runoff from the Coast Ranges, depending on the intensity of the storms. Orestimba Creek is representative of the small western tributaries to the San Joaquin River.

Orestimba Creek is being sampled for water-borne constituents and biological characteristics as part of the Trend Network for Streams.

Orestimba Creek Basin

Orestimba Creek, looking downstream, showing agricultural drain
(Photograph by Cathy Munday, U.S. Geological Survey)

Orestimba Creek, below bridge, looking downstream
(Photograph by Cathy Munday, U.S. Geological Survey)