h running water. The date was from March 25 to 29. Anza
and Font went at almost the same time of year (March 31-April 1, 1776)
from Warm Springs to Rodeo, and report 20 or 21 arroyos. Of these only 2
or 3 contained abundant water; approximately 10 had only a small amount.
The rest were either not described or were without water. Since there
can have been no profound alteration in climate or geography in the few
years between the two expeditions, the difference must be accounted for
on the basis of relative precipitation during the preceding winters.
Such a theory is supported by Font's statement (F2, p. 418) regarding
the marshes and lagoons in Gilroy Valley: "Since it had not rained much
this year it was quite dry...."

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 disp