Page 36 - Beaumont Basin Watermaster

Section 3
Status of the Basin and Administration of the Judgment

Results of the analysis show an increase in groundwater storage within the adjudicated basin
of approximately 1,362 acre-ft between Fall 2016 and Fall 2017. 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 2017 was 15,867 ac-ft (see
Table 3-3). Total artificial recharge in calendar year 2017 was 14,940 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:

15,867 + 1,362 – 14,940
OSY = = 2,289 ac-ft
1

It is emphasized that the OSY, as presented herein, is based on one year of data. When
evaluated on a long-term basis, this methodology can be used to estimate the long-term Safe
Yield of the basin, as defined in the Beaumont Basin Judgment. As required by the
Judgment, the Safe Yield of the basin was reevaluated in 2013. The Safe Yield will be
reevaluated again in 2023.

Beaumont Basin Watermaster 2017 Annual Report – DRAFT – February 2018 3-13