WACO Orange County Water District Future Water Demands and Water - - PowerPoint PPT Presentation

WACO

Orange County Water District Future Water Demands and Water Supply Projects

September 7, 2018

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WACO Tentative Schedule

• September – OCWD – John Kennedy

Future OCWD Demands/Supplies/Potential Projects/Operations

• October – MWDOC – Karl Seckel

Orange County Water Reliability Study

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OCWD Producers

• 13 Cities
• 5 Retail Water

Districts

• 1 Investor

Owned Water Utility

Historical OCWD Service Territory Total Water Demands (afy)

447,000 afy

Future OCWD 2040 Water Demand Projections (afy)

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Future Water Demand Estimate Information/Issues

• Previous estimates were much higher
• New state legislation impact – water retailors will be

given water use objectives (water budgets)

• Water demands can annually fluctuate due to economic
• r climate variations
• Will state mandate temporary conservation requirements

during future drought cycles as it did in 2015-16?

• Need to continually assess

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Current OCWD Service Territory Water Supply Sources (afy)

Total Water Demands of 410,000 afy

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26%

Future Projected OCWD Service Territory Water Supply Sources (afy)

Total Water Demands of 447,000 afy

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BPP = ~ 80% Year 2040

28%

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Historical SAR Base Flows (afy)

34,000 afy SAR Judgment minimum

SAR Base Flows

• Are primarily wastewater treatment plant effluent
• Predicting future flows is very difficult

– Conservation reduces flows to waste water treatment plants – Lower groundwater levels in the upper watershed encourages recharge of SAR flows – Additional GW pumping along the river encourages greater recharge by SAR – Dry weather reduces flows – Upper watershed growth can increase flows

• SAWPA Report – 52,000 afy
• Seems likely that flows will decline as agencies reuse supplies
• Habitat issues may require water to remain in SAR
• 34,000 afy absolute minimum per the 1969 SAR Judgment

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SAR Storm Flow Recharge vs. San Bernardino Rainfall: 2004-15

5 10 15 20 25 30 35 40

Annual San Bernardino Rainfall (Inches)

20,000 40,000 60,000 80,000 100,000 120,000

Annual SAR Storm Flow Recharged (AF)

09-10 04-05 10-11 05-06 11-12 06-07 12-13 07-08 13-14 08-09 14-15

Linear Best Fit: Storm Flow Recharged = 2,738 X SB Rain + 9,125 R2 = 0.77 Annual data based on July - June water year Average

1 inch of rainfall = ~3,300 afy

OCWD has a cooperative program with the ACOE to conserve water behind Prado Dam

SAR Storm Flow

• Tied to rainfall, upper SAR Watershed activities

and Prado Dam operations

• Prado Dam

– 505 feet year round – extra ~7,000 afy – 508 feet in the future?

• Siltation issues – loss of ~ 25,000 afy in 50

years

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5 10 15 20 25 30 35 40

Annual Rainfall at OCWD Field Headquarters (Inches)

30,000 60,000 90,000 120,000 150,000 180,000

Incidental Recharge (AF)

16-17 06-07 08-09 15-16 07-08 10-11 09-10 14-15 04-05 05-06 11-12 12-13 13-14

Linear Best Fit: IR = 4,254 X FHQ Rain + 2,818 R2 = 0.93 Annual data based on July - June water year

Incidental Recharge vs. FHQ Rainfall (2004-17)

50%

1 inch of rainfall = ~4,500 afy

Incidental Recharge and SAR Storm Flow Recharge at Various Rainfalls

SB Rainfall (in) FHQ Rainfall (in) Incidental Recharge (AFY) SAR Storm Flow Recharge (AFY) Total (AFY) 10 8.3 39,500 34,400 73,900 13 11.4 53,100 44,700 97,800 15 13.4 61,900 51,600 113,500 18 16.5 75,500 61,900 137,400 27 25.8 116,400 92,900 209,300

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Possible Future Local Water Supply Projects

Project Amount (afy) Poseidon Resources 56,000 CADIZ 5,000 to 10,000 West Orange County Well Field 3,000 to 6,000 Prado Dam 505’ year round ~7,000 MWD Carson IPR Project Up to 65,000 afy Purchasing Upper SAR Watershed Supplies ? GWRS RO Brines Recovery 5,000 to 10,000

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• Local water supplies are currently ~ 450,000 afy

below MWD Integrated Resources Plan 2040 target

• MWD staff is recommending to increase LRP

subsidy cap from 68,000 afy to 150,000 afy to encourage additional local supply development

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Information From August 21, 2018 MWD Conservation and Local Resources Committee

OCWD Basin Management Policy

• 500,000

0 AF

No BPP change; Purchase 65,000 afy of imported water

Increase BPP; Reduce or stop purchases of imported water Purchase additional imported water and/or Reduce BPP to reduce overdraft Purchase additional imported water and Reduce BPP to reduce overdraft MWD CUP 66,000 AF SARCCUP 36,000 AF

• 150,000
• 200,000
• 350,000
• 400,000

No BPP change; Purchase 65,000 afy of imported water; Reduce the overdraft

OCWD Groundwater Basin Accumulated Overdraft

Target Overdraft

Basin Operating Range

Wet Dry

End of Presentation

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Estimated Year 2022 Project Unit Cost

Item Unit Cost

(30 year deal)

Unit Cost

(35 year deal)

Treatment Plant Cost $1,916/af $1,854/af Distribution (“Place Holder amount”) $350/af $350/af Total Project Cost $2,266/af $2,204/af MWD LRP Subsidy ($475/af) ($475/af) Total Net Project Unit Cost $1,791/af $1,729/af Estimated 2022 MWD Rate (4.1%

annual increases)

$1,255/af $1,255/af Difference $536/af $474/af

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WY 2017-18 Groundwater Balance

Inflows & Outflows (acre-feet) Original Budget (Rain~11 in.) Actual (Rain 3.86 in.) Difference SAR Base and Storm Flow Recharge 103,500 89,500

• 14,000

Incidental Recharge 52,000 26,200

• 25,800

GWR System (Forebay & Barrier) 103,000 105,500 2,500 MWD Supplies (including CUP) 65,000 66,100 1,100 Other (Alamitos Barrier, Talbert OC-44) 2,000 900

• 1,100

Total Water Into Basin 325,500 288,200

• 37,300

Total Basin Pumping @ 75%

• 203,000
• 237,200
• 34,200

Storage Change +122,500 +51,000 Accumulated Overdraft 205,500 277,000

WY 2018-19 Projected Groundwater Balance

Inflows & Outflows (acre-feet) Average Hydrology (Rain~13 in.) SAR Base Flow Recharge 70,000 SAR Storm Flow Recharge 51,000 Incidental Recharge 61,000 GWR System (Forebay & Barrier) 103,000 MWD Supplies (including CUP) 65,000 Other (Alamitos Barrier, Talbert OC-44) 2,000 Total Water Into Basin 352,000 Pumping @ 77% BPP

• 322,000

Storage Change +30,000 Accumulated Overdraft (June 30, 2019) 247,000

General Comments

• If you think ultimately the project will be needed, then you should build it now as you may never

get another opportunity.

• No one knows what the impact of changing weather patterns will be in the future.
• No one can guarantee that we will have enough water in the future – there are just too many

variables and uncertainties.

• For something as important as water – you always want to err on the side of having too much.
• Scientist studying tree rings have indicated CA has experienced 30 to 50 year drought cycles in

the past – how would CA survive such a scenario now that 40 million people reside in the state.

• Why are many agencies working to reduce their dependence upon imported water supplies?
• What is the value of having a water supply source in your backyard vs a source 300 to 400 miles

away?

• At worst the Poseidon project is an insurance policy against various future water shortage

scenarios assuming the cost of the water never becomes cheaper than imported water.

• How many times in our lifetime are we going to see a private company invest tens of millions of

dollars to permit such a plant?

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OC Water Reliability Study

• Is an excellent document.
• Difficult to predict the future.
• Is based upon numerous reasonable assumptions about the future.
• You could make reasonable changes to those assumptions and get different

results.

– Difficult to predict climate change – Prado Dam Siltation – SAR Base Flows – SGMA Impacts

• Assumes no WQ issues impacting water supply availability - With advanced

detection techniques, chemicals in very small quantities are being detected in water supplies – ppt – agencies may need to use reverse osmosis in the future

• n all drinking water supplies.

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