Page 141 - 1915, Springs of CA.

HOT SPRINGS. 131
BROCKWAY HOT SPRINGS (PLACER 8).
The only noteworthy thermal springs in the basin of Lake Tahoe
are at the north end of the lake, near Stateline Point, at a fishing and
boating resort, known as Brockway, where in 1909 a hotel and four
cottages provided accommodations for 100 people. The springs rise
in the lake within a few feet of the shore, bubbling up from numerous
vents, principally at two localities. One of these localities is at the
boat pier, where one spring has been cemented so as to form a drinking
basin near the lake edge. A temperature of 137° was recorded in
this spring, and the discharge was about 3 gallons a minute. A plan
had been considered for making a warm swimming pool by construct-
ing a concrete wall around the springs in the lake at this place.
Water from another group of springs, which is situated in the lake
near its edge, about 150 yards northwestward, is pumped to a tank
near by and used for bathing and for laundry purposes. The water
is faintly sulphureted but seems to be only slightly mineralized other-
wise, for it is very soft and excellent for laundry use.
The springs rise from granodiorite which is overlain on the slopes
above by andesitic lava. A probable fault has been mapped by
Lindgren * as passing southeastward through the lake, about one-
third of a mile west of the springs.2 This fault appears to furnish
the most plausible explanation for the existence of the springs.

GROVERS HOT SPRINGS (ALPINE 1).
In Alpine County, about 4 miles west of Markleeville and near the
southern extension of the Sierra Valley fault, considerable heated
water rises at Grovers Hot. Springs from a dozen springs and seepages
in two marshy areas about 100 yards apart, at the edge of a meadow
on the southern side of Markleeville Creek. The principal springs
range in temperature from 128° to 146° and their combined dis-
charge perhaps 100 gallons a minute irrigates the meadow.
In 1909 a pool 3 or 4 feet deep and about 30 feet square was used
for bathing, and the place has been visited as a camping resort for
many years.
Lime carbonate has been deposited by the springs and is especially
noticeable below several of the springs that flow down over a terrace
or bank that has probably been formed by the carbonate material.
The slopes that surround the springs are granitic, but less than half a
mile to the east there is lava that possibly has some relation to the
hot water and to its content of lime carbonate. The fact that an
extensive fault passes close to the springs suggests, however, a more
plausible cause for the issuance of the hot water.
1 Lindgren, Waldemar, U. S. Geol. Survey Geol. Atlas, Truckee folio (No. 39), 1897.
2 This fault is not shown on map No. 1 of the atlas accompanying the report of the California State Earth-
quake Commission, probably through oversight.