Upper Penitencia Creek, on the eastern side of Santa Clara Valley, has locally significant potential for stream restoration and anadromous fish recovery. The Upper Penitencia Creek Historical Ecology Assessment documents aspects of Upper Penitencia Creek's hydrogeomorphology and riparian ecology prior to major Euro-American modification. It describes the historical (ca. 1850) channel alignment, dry season hydrology, and riparian corridor of the creek as interpreted from early maps, textual records, and photographs. It also explores the nature and timing of the diversion of Upper Penitencia into Coyote Creek.