Hydrologic data, 1965 - Department of Water Resources - State of ...

eing made to improve the network of stations from which data
are collected.
Ground water is the source of supply for about
one-half of the water beneficially used in California. Ground
water levels are essential for the knowledge of and the changes
in the ground water situation. The Department in cooperation
with many federal, state, and local agencies attempts to col-
lect sufficient ground water level measurements to determine
this information.
Surveillance networks for both surface and ground
water quality are designed to provide information to describe
the resource, determine trends and ranges of values, and to
establish base line conditions. A separate, cooperative pro-
gram with the U. S. Bureau of Reclamation determines the
status and extent of sea water incursion in the Sacramento-San
Joaquin Delta.