Page 33 - Beaumont Basin Watermaster - DRAFT 2016 Annual Report

Section 3
Status of the Basin and Administration of the Judgment

3. Attributes were assigned to each grid cell including groundwater level change and
specific yield.

4. The resulting attribute table was processed in a Geographic Information System (GIS)
for calculating the change in storage.
The specific yield distribution used for the analysis was obtained from the calibrated
groundwater flow model used to evaluate the safe yield of the Beaumont Basin, as
summarized in TH&Co (2015).

Results of the analysis show an increase in groundwater storage within the adjudicated basin
of approximately 1,279 acre-ft between Fall 2015 and Fall 2016. The net storage increase is
attributable to artificial recharge of imported water at the Noble Creek Artificial Recharge
facility. Most of the western and southern areas showed decreases in groundwater in
storage

3.7 Operating Safe Yield

For purposes of this annual report, the annual operating safe yield (OSY) describes the net
infiltration to the adjudicated groundwater basin (not including artificial recharge) for any
given year. It is noted that the OSY is different than the Operating Yield, which is a function
of the unused overlyer production (Appropriative Water) and Temporary Surplus, as
described in the Beaumont Basin Judgment (San Timoteo Management Authority v. Banning
et al., 2004).

Operating safe yield is estimated based on the following equation:

OSY = ΣP + ΔS - ΣAR
ΔT

where: ΣP = The sum of groundwater production (ac-ft)

ΔS = The change in groundwater storage (ac-ft)
ΣAR = The sum of groundwater recharge (ac-ft)

ΔT = The time over which the OSY is estimated (years)

Total Beaumont Basin groundwater production in calendar year 2016 was 13,777 ac-ft (see
Table 3-3). Total artificial recharge in calendar year 2016 was 10,746 ac-ft (see Table 3-4).
It is noted that only the Noble Creek Recharge Facility recharge was used in the analysis of
OSY (recharge at the Little San Gorgonio Creek facility is not included because it is outside
the adjudicated area). The change in groundwater storage estimate is based on the analysis
of groundwater levels described earlier in this TM. The period of time over which the OSY is
evaluated is one year. The resulting OSY is estimated as:

Beaumont Basin Watermaster 2016 Annual Report – DRAFT – August 2017 3-12