Water Supply Assessments
LADWP Board Meeting July 21, 2015
David R. Pettijohn Director of Water Resources
Los Angeles Department of Water and Power
State Law Requirement
Water Code 10910-10915 – As part of CEQA, City is required to
prepare a Water Supply Assessment (WSA) for large developments.
– Determine if total projected water supplies available during normal, single dry, multiple dry years over a 20-year period will meet project’s demand, in addition to City’s future demands
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Water Supply Assessment
• Identification of Water Supplies
• Detailed Project Description
• Calculation of Project’s Water Demand
• Compliance with current ordinances
• Determination of whether the Project’s water demand was included in the most recently adopted UWMP
• Statement of Findings
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520000
570000
620000
670000
720000
770000
2015 2020 2025 2030 2035
Acre
-Fe
et
Year
Forecasted WSA Project Demand
Forecasted Demand
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77%
23%
Future Demand Growth
Urban Water Management Plan
Supply Growth
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Today
Future
When Would We Not
Recommend WSA Approval?
Water Code 10911 – Assess plans for acquiring additional
water supplies
Supplies Impacted by: – Loss of supply(s);
– Catastrophic disruption;
– Natural disaster;
– Regulatory / Environmental; or
– Drought Year Supply Shortage
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11 Recycled Water
79 Local Groundwater
61 Los Angeles
Aqueduct
334 MWD
0
100
200
300
400
500
600
Projected 15/16 Supplies
Th
ou
sa
nd
Acre
-Fe
et
(TA
F)
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Governor’s Executive Order (474 TAF)
Mayors ED5 (485 TAF)
Current Dry Year Supplies
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Projects That Require a WSA
Water Code 10912 – Residential development > 500 dwelling
units
– Shopping center/ business establishment > 500,000 s.f.
– Commercial office building > 250,000 s.f.
– Hotel/Motel > 500 rooms
– Industrial development > 40 acres of land or 650,000 s.f. floor space
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Water Demand Estimate
• Net Additional Water Demand = Proposed – Existing – Conservation
• Proposed Indoor Building Outdoor Landscaping Cooling Towers
• Existing Water Use Billing Records
• Conservation
Required by City Ordinances Additional Voluntary Recycled Water
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Proposed Water Demand
• Indoor Building – Sewer Generation Factors (SGF)
• Cooling Towers • Outdoor Landscaping
– Model Water Efficient Landscape Ordinance
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Slide
Water Use Factors
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Slide
Demand Calculations
Required for Board Approval
Current Adopted UWMP
– Water demand projections based on Southern California Association of Governments (SCAG) demographic projections
Project Consistency with SCAG
City’s General Plan
– Community Plans: based on the SCAG data.
Determination of Adequate Supplies
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WSA Findings
• Determination of sufficient water supplies to meet Project’s demand during normal, single dry, and multiple dry years for the next 25 years
• Determination of Project’s water demand falls within the City’s water demand growth projection
• Estimate of Project’s Additional Water Demand
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