OCWD Management Area
Table 11-1: Baseline Projected Future Salt Inflows
Volume (acre-feet/yr)
TDS Conc. (mg/L)
Mass (tons/yr)
Source of Water Recharge
Deep percolation of precipitation*
6,500
100
900
Percolation of applied water*
9,000
1,900
23,200
Subsurface inflow*
44,500
1,290
78,200
SAR base flow
52,000
700
49,500
SAR storm flow
50,000
200
13,600
Recycled water (GWRS)
133,000
86
15,600
Alamitos Barrier
2,500
350
950
MWD imported water
0
0
0
Total
297,000
449
181,200
*Component of unmeasured recharge
The Baseline Scenario assumes that no imported water is used for recharge for the 30-year period and is utilized to compare with other model runs and determine how changing model inputs affect the predicted concentration. The projected trend for TDS for the Baseline declines from the current ambient groundwater concentration of 603 mg/L to 569 mg/L in 30 years as shown in Figure 11-1. Seven additional scenarios were run to model different quantities of recharge source water. The projected 30-year TDS for these scenarios range from 559 mg/L to 580 mg/L. This shows the tremendous impact of low-TDS GWRS water in lowering the overall salinity in the basin over time regardless of how much water is obtained from other recharge sources, such as higher TDS imported water.
BASIN 8-1 ALTERNATIVE 2022 UPDATE
Sustainable Management: Water Quality 11-1
Appendix F - 165
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