 The creek leaves Isabel Valley and continues northwest, crossing Mount Hamilton Road then along the eastern and northern flanks of Mount Hamilton, joining Smith Creek about 15.3 km WNW of Mount Hamilton at to form Arroyo Hondo which, in turn, joins Calaveras Creek in Calaveras Reservoir.Calaveras Creek exits the reservoir and joins Alameda Creek before final terminating in San Francisco Bay.Steelhead trout ("Oncorhynchus mykiss") are native to Isabel Creek, as noted by John Otterbein Snyder who collected specimens in 1898.