Page 34 - Beaumont Basin Watermaster

Section 3
Water Quality Conditions

3.6 Changes in Groundwater Levels in the Beaumont
Basin

3.6.1 Analysis of Groundwater Level Changes
Changes in groundwater flow and groundwater levels between 2017 and 2018 were evaluated
using a calibrated groundwater flow model that was previously developed to reevaluate the
Safe Yield of the Beaumont Basin (TH&Co, 2015) and refined in May 2016 (TH&Co, 2016).
For this analysis, the existing calibrated model was updated with groundwater pumping,
recharge, and groundwater levels through the end of 2018. A model-generated groundwater
contour map was created for December 2018 and compared to the model-generated
December 2017 groundwater contour map in order to evaluate changes in groundwater flow
patterns and basin-wide changes in groundwater levels. The model-generated groundwater
contour maps for 2017 and 2018 are shown on Figures 3-6 and 3-7, respectively.

Groundwater flow direction and gradient within the Beaumont Basin varies depending on
location with respect to a groundwater flow divide which occurs in the center of the basin
approximately coincident with the Noble Creek drainage. In the western portion of the basin,
groundwater generally flows toward a groundwater depression near BCVWD Well 29 or west
towards San Timoteo Wash. In the eastern part of the basin, groundwater flows to the
southeast towards the City of Banning. The groundwater flow directions did not change
significantly between 2017 and 2018.

Basin-wide groundwater level trends in the Beaumont Basin were evaluated based on
hydrographs from eights key wells and the groundwater level change map developed by
subtracting the 2017 groundwater surface from the 2018 groundwater surface. The total
change in storage between the Fall 2017 and the Fall 2018 is shown in Figure 3-8. In the
northwest portion of the basin (YVWD 34 and Singleton Ranch 7), groundwater levels
remained stable in CY 2018. At Tukwet Canyon Golf Club C, groundwater levels continued a
steady decline in 2018 that has been observed since 2003. When evaluated on a long-term
basis, groundwater levels in wells in the western portion of the basin have shown a general
long-term decline since approximately 2005.

As shown on Figure 3-9, groundwater levels in the north central portion of the basin were
relatively stable or increasing in the vicinity of the Noble Creek Artificial Recharge facility.
Groundwater levels in BCVWD NC-4D, located on the center of the recharge facility rose
approximately 17 ft between November 2017 and November 2018 (see Figure 3-8). The
groundwater flow model did not replicate the magnitude of measured groundwater level rise in
the Nobel Creek Recharge area and, as such, the groundwater storage change from the
model (Figure 3-8) appears to underestimate the storage change suggested by the
groundwater levels. .

In the south-central portion of the basin, groundwater levels at Oak Valley No. 1 continue to
decline in 2018, but started to recover at the end of the year. At BCVWD Well No. 2,
groundwater levels rose in January 2018, declined in April, and began rising again in July. At
Banning Well C-4 (southeast Beaumont Basin), groundwater levels were rising in April,
declined in the summer, and began increasing in December.

Beaumont Basin Watermaster 2018 Annual Report – DRAFT - February 2019 3-12