OCWD Groundwater Basin Storage Evaluation Joint Planning Committee - - PDF document

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Sep 11, 2022 454 likes •529 views

7/26/2018 OCWD Groundwater Basin Storage Evaluation Joint Planning Committee July 25, 2018 Current Basin Management Policies 0 AF Increase BPP; Reduce or stop purchases of imported water 100,000 No BPP change; Purchase enough imported

SLIDE 1

7/26/2018 North Basin 1

OCWD Groundwater Basin Storage Evaluation

Joint Planning Committee July 25, 2018

Current Basin Management Policies

‐ 500,000 0 AF ‐ 100,000

No BPP change; Purchase enough imported water to help balance recharge with expected pumping

Increase BPP; Reduce or stop purchases of imported water No BPP change; Purchase enough imported water with goal of reducing overdraft based on expected pumping

‐ 150,000

Purchase additional imported water and/or Reduce BPP to reduce overdraft Purchase additional imported water and Reduce BPP to reduce overdraft

‐ 350,000 ‐ 300,000

MWD CUP 66,000 AF SARCCUP 36,000 AF

Target Accumulated Overdraft Range

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7/26/2018 North Basin 2

Questions to Answer

How much storage do we need for a drought? Is there storage space remaining for other programs?

2011 to 2016 Drought

Driest or second driest period in SoCal since 1400s
Significant reduction in rainfall – 55% of average
Captured SAR storm flows reduced
Less Natural Incidental recharge
Year 5 of drought cycle
MWD deliveries were reduced
Governor required 25% conservation

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7/26/2018 North Basin 3

During 2011-16, basin storage decreased 161,000 af (or 145,000 af without MWD CUP)

218,000 379,000

Acre‐feet

(16,000 is CUP)

Three Drought Scenario Projections

# Description 1 Repeat 2011 to 2016 drought w/current demands & supplies 2 Repeat 2011 to 2016 drought; State does not reduce water demands by 25% in Year 5; MWD deliveries cut in years 4 & 5 3 Scenario #2 plus MWD delivery reductions in years 6 & 7

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7/26/2018 North Basin 4

Accumulated Overdraft Projections

‐500,000 ‐450,000 ‐400,000 ‐350,000 ‐300,000 ‐250,000 ‐200,000 ‐150,000 ‐100,000 ‐50,000 2018 2019 2020 2021 2022 2023 2024 2025 Base Case Scenario 1 Scenario 2 Scenario 3

287,000 180,000 af Drought ends

Findings

1. Lower total water demands over last 10 years have

reduced impacts from drought cycles

2. GWRS Final Expansion will increase base supplies

improving drought resiliency

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7/26/2018 North Basin 5

Recommendations

1. Accumulated overdraft target and basin storage

triggers can be lowered 50,000 af without jeopardizing drought preparedness.

2. Maximum accumulated overdraft should remain at

500,000 af.

3. Storage agreements should be contained within

SARCCUP storage, at least until MWD CUP terminates in 2028.

Proposed Basin Management Policy Revisions