Examination of the modern maps is instructive. The U. S. Geological Survey quadrangles for the Bay Area were mapped in the decade 1895 to 1905, with subsequent re-editing. Thus the picture presented antedates the disruption of natural conditions caused by the population expansion of this century. The USGS sheets now show 20 streams between Milpitas and Rodeo which were named on the maps, or whose names are otherwise well recognized. These are, from south to north: Arroyo Coches Creek, Calera Creek, Scott Creek, Toroges Creek, Agua Fria Creek, Agua Caliente Creek, Mission Creek, Alameda Creek, San Lorenzo Creek, San Leandro Creek, the creek flowing past Mills College, the creek flowing out of Diamond Canyon through Fruitvale, Indian Gulch, Claremont Creek, Strawberry Creek, Codornices Creek, Wildcat Creek, San Pablo Creek, Pinole Creek, and Rodeo Creek. In addition there are approximately 12 unnamed creeks or arroyos descending the front slope of the hills onto the plain. The total, 32, conforms very closely with the descriptions left by the Spaniards in 1772 and 1776. It is further to be noted that the government surveys of the period of 1900 showed all these streams as intermittent and therefore dependent for their flow upon the winter rainfall. Thus it is quite probable that in late March the amount of water might be copious (as in 1772) or relatively scanty (as in 1776). The conclusion seems warranted that, apart from dessication induced by such factors as soil damage, overgrazing, and diversion for minor irrigation projects, the local water supplies have not diminished since 1770. It then follows that under primitive conditions the natives had substantially the same quantity of water at their disposal as is available in the same area today.