Page 376 - 1915, Springs of CA.

356 SPRINGS OF CALIFORNIA.

which issues in two small marshy areas about 100 yards apart, comes
from the Franciscan group of rocks that form the higher slopes of
the mountain. Very little water flows from the springs, but they
could probably be made to yield 8 or 10 gallons a minute.

CHAPARRAL SPRING (CONTRA COSTA 6).
A few small springs in the hills north of Mount Diablo are used to
supply water troughs for cattle. One of the chief of these is Chaparral
Spring, whose water issues in a small pool on the side of a ravine 3
miles southeast of Clayton and is piped a few yards to a trough. The
water seeps from a bank of crushed shales that dip nearly vertically.
It is of good quality, but the flow is very small. A similar spring in
another ravine half a mile southeastward also supplies a watering
trough.
PURITY SPRING (MARIN 4).
Purity Spring is situated on the slopes near Sausalito, on the
northern side of San Pablo Bay. It yields a considerable flow of
water that is not notably mineralized. For a number of years it
has furnished part of the municipal water supply and the water has
also been bottled, under several names, for table use.

SPRINGS AT VETERANS' HOME (NAPA 11).
The main supply of water for the Veterans' Home near Yount-
ville is obtained from a spring on the adjacent hillside. This spring
is about a quarter of a mile southwest of and 200 feet above the
principal buildings, at a point where there was originally a small
flow. The water now rises in an excavation about 10 feet wide, 25
feet long, and 1 or 2 feet deep within a spring house. Five holes 2
inches in diameter and 10 to 25 feet deep were drilled in the bottom
of the basin that was formed, and the yield of water is said to have
been increased by this means from a total flow of 7,000 gallons a day
to one of 24,000 gallons (from about 5 to 17 gallons a minute). The
water is piped to a reservoir near by and thence to the grounds of
the institution. There is a small amount of the iron-secreting
Crenothrix in the basin at the springs, and the water is faintly sul-
phureted but of good quality.
Another spring issues in an excavation at the side of a small creek
about 300 yards down the slope from the main spring. It yields
about 4 gallons a minute and supplies a watering trough a few yards
away. The basin at this spring also contains a small amount of
brown iron-colored material.
These springs issue from porous tuffaceous layers in rhyolitic lava
that covers the slopes along this part of Napa Valley.