Page 35 - Beaumont Basin Watermaster

Beaumont Basin Watermaster
2013 Reevaluation of the Beaumont Basin Safe Yield 3-Apr-15

Accordingly, recharge from the LSGCRF was delayed by 4 years when applied to the water
balance (see Table 2). Artificial recharge at the NCRF began in 2006. Operational data at this
facility has shown that surface water reaches the upper aquifer groundwater surface within a few
months of introduction in the spreading basins (Geoscience, 2006c). Recharge from the NCRF
was applied to the water balance the same year it was applied at the land surface.

4.2 Groundwater Discharge

4.2.1 Groundwater Pumping
The primary source of groundwater discharge from the Study Area is pumping from wells (see
Figure 9; Appendix E). Although groundwater production in the Study Area has increased
significantly since the earliest records (late 1920s), historical records show a number of pumping
patterns, primarily dictated by land use. Between approximately 1927 and 1950, average
groundwater production was approximately 3,600 acre-ft/yr (see Figure 27) and the primary use
of water was agriculture. Between 1950 and 1965, average annual groundwater production
increased to approximately 6,500 acre-ft/yr with increasing agricultural water use and municipal
water use. In the late 1960s, 1970s and into the 1980s, average annual groundwater production
stabilized at approximately 5,900 acre-ft/yr. With increasing development in the Beaumont area,
groundwater production increased to approximately 8,300 acre-ft/yr in the 1990s and then nearly
doubled to an annual average of 15,300 acre-ft/yr between 2000 and 2012. The greatest annual
groundwater production occurred in 2007 when approximately 19,700 acre-ft was extracted.

4.2.2 Evapotranspiration
Evapotranspiration (ET) is the loss of water to the atmosphere from free-water evaporation, soil-
moisture evaporation, and transpiration by plants (Fetter, 1994). Evapotranspiration was
estimated for the Study Area based on the average annual ET o at the University of California,
Riverside CIMIS station, located approximately 12 miles west of Study Area. While this CIMIS
station may not fully represent the unique climatic conditions that occur in the Beaumont Basin
(see Section 3.2.2), short of additional data within the basin, it is the closest and most
representative station available. The majority of ET occurs at the land surface although
evaporation and transpiration will also remove water from the shallow subsurface. A shallow
subsurface ET extinction depth of 15 feet was assumed for the Study Area based on extinction
depth estimates for nearby basins (Danskin et al., 2006). In the Study Area, only shallow
groundwater in the riparian area along San Timoteo Creek is subject to ET.

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