No kidding. "Mountains" indeed.
From AB 1788:
2)Designates the territory of the Conservancy as follows:
a) The Sierra Nevada Region consists of 20 designated
counties, from Lassen in the north to Kern in the south.
This region is further subdivided into five subregions,
each consisting of groups of adjoining counties;
b) The Core Sierra Nevada Region consists of an area
described by the 1,500-foot elevation contour on the
western slope of the Sierra Nevada and by named highways
and other natural and human features delineating the
northern, eastern, and southern boundaries of the core
region; and,
c) The territories of the California Tahoe and the San
Joaquin River Conservancies are excluded from these
regions.
(snip)
1) The region defined in AB 1788 includes large portions of the
Central Valley and, in Tehama, Fresno, and Kern Counties, it
extends entirely across the valley into the Coast Range. By
contrast, the western boundary of the region defined in AB
2600 stops at about the 500-foot elevation contour and
includes only small portions of the extreme eastern edge of
the valley floor. The core region defined in AB 1788, where
presumably the Conservancy's activities will be concentrated,
is significantly smaller than the region defined in AB 2600.
In particular, because AB 1788 uses the 1,500-foot elevation
contour as the western boundary of the core region, long
reaches of the deep canyons of the principal rivers of the
Sierra and many lakes and reservoirs situated below that
elevation are excluded from the core region.