This line shapefile represents changes in groundwater levels in California. These data represent groundwater changes between spring 2010 and spring 2013. The contours approximate change in the groundwater levels for the unconfined to uppermost semi-confined aquifers and is based on a subset of all of the measurement points, which were selected based on measurement data and well construction information (where available).This layer is intended to be used as a compliment to data, reports, and other information provided by the California Groundwater Information Center.