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REDUCING POTABLE WATER USED FOR IRRIGATING NEW LANDSCAPING IN CALIFORNIA Dave Jaeckel|Michelle Camp|Sarah Sugar Yale School of Forestry and Environmental Studies
Source: The New York Times
Presentation Roadmap
• Overview of “Waste or Unreasonable Use”• California Residential Development Trends• Alternatives to Turf and Potable Water• Potential Water Savings • Costs of Saving Water
• Summary• Questions?
2
Sources: United States Drought Monitor, NBCnews.com
Roadmap
3Overview of “Waste or Unreasonable Use”
Waste or Unreasonable Use
Sources: California Constitution, SWRCB
“It is hereby declared that because of the conditions prevailing in this State the general welfare requires that the water resources of the State be put to beneficial use to the fullest extent of which they are capable, and that the waste or unreasonable use or unreasonable method of use of water be prevented, and that the conservation of such waters is to be exercised with a view to the reasonable and beneficial use thereof in the interest of the people and for the public welfare.” (Cal. Const. art. X, §2)
• “Reasonable use” is not a static concept, and depends on the circumstances of the case (e.g., periods of long drought)
• SWRCB has the authority to order the termination of misuse
4Overview of “Waste or Unreasonable Use”
Seven-Factor Test
Sources: SWRCB, Water Rights Decision 1600 (1984)
• SWRCB uses a seven-factor test to evaluate whether a use is unreasonable:
1. Other possible beneficial uses for the water
2. Whether the excess water serves other beneficial uses
3. The probable benefits of water savings
4. The amount of water reasonably required for beneficial use
5. The amount and reasonableness of the cost of saving water
6. Whether the methods of saving water are conventional
7. The availability of a physical solution
5
Projected Development (2015-2030)
Sources: United States Census Bureau
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3
4
5
Building Permits1. Los Angeles: 252,3702. Riverside: 169,1083. San Diego: 124,8144. San Bernardino: 116,2075. Santa Clara: 96,411
*Includes single family, two family, three and four family, and five or more family permits.
Higher ET, larger yard sizes, more potable water demand
California Residential Development Trends
6Solutions
Solutions to Reduce Potable Water Use
Sources: California Model Landscape Ordinance, Pacific Institute
• Water smart landscaping practiceso 75% less water requirements than cool season turf (uses
drip and microspray irrigation)o Cost effective
• Alternative water sources (non-potable water)o Rainwater harvestingo Graywater systems
Focus on new residential development for traction
çAvg. Daily Graywater Generated: 84 gallons(3 people per household)
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Estimated Potable Water Need for Irrigation (Turf)
71,687 – 86,216 gallons / year
Avg. Roof Size: 1,500 square feet(1.26 inches average monthly precipitation LA County)
Irrigated Yard: 3,370 square feet(cool season turf grasses with sprinklers)
çEx: New Los Angeles Single Family Home
çGraywater Potential: + 30,660 gallons per year
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Estimated Potable Water Need for Irrigation (Low Water)
17,921 – 21,554 gallons / year
53,766 – 64,662 gallons / year savings
Rainwater Harvesting Potential:+ 11,310 gallons per year
Irrigated Yard: 3,370 square feet(low water plantings with drip or microspray irrigation)
çEx: New Los Angeles Single Family Home
9
Water Savings // Water Smart Landscaping
Sources:
Factor 4: Potential Water Savings
How much potable water could be saved if new development in California installed low water landscapes?
10
Water Savings // Water Smart Landscaping
Sources: Pacific Institute, DWR, PPIC, US Census Bureau
Water Demand (DWR)
Water Demand (PPIC)
0
5000
10000
15000
20000
25000
Estimated Average Annual Outdoor Potable Water Use in New Development (2004-2013)
Turf
Low Water Plants (Upper Range)
Low Water Plants (Lower Range)
Acr
e Fe
et/Y
ear
Factor 4: Potential Water Savings
12,9
22-1
3,71
5 AF
/Y S
avin
gs
12,9
22-1
5,88
9 AF
/Y S
avin
gs
12,922-14,799 AF/Y savings switching from turf to low water plants
11
Water Savings // Water Smart Landscaping
Water Demand (DWR)
Water Demand (PPIC)
0
100000
200000
300000
400000
500000
600000
Estimated Outdoor Water Use in New De-velopment, 2015-2030: Turf vs Low Water
Scenarios
Turf
Low Water Plants (Upper Range)
Low Water Plants (Lower Range)
Acr
e Fe
et
Factor 4: Potential Water Savings
320,
444-
375,
404
AF S
avin
gs
320,
444-
338,
093
AF S
avin
gs
320,444-356,749 AF savings switching from turf to low water plants
Sources: Pacific Institute, DWR, PPIC, US Census Bureau
12
Water Savings // Water Smart Landscaping
2015-2020 2020-2025 2025-20300
100000
200000
300000
400000
500000
600000
Estimated Outdoor Water Use in New De-velopment, 2015-2030: Turf vs Low Water,
5 Year Scenarios
Turf
Low Water Plants (Upper Range)
Low Water Plants (Lower Range)
Acr
e Fe
et
Factor 4: Potential Water Savings
320,
444-
375,
404
AF/Y
Sav
ings
106,
815-
125,
135
AF/Y
Sav
ings
106,815-125,135 AF savings every 5 years
Sources: Pacific Institute, DWR, PPIC, US Census Bureau
213,
629-
250,
270
AF/Y
Sav
ings
13Factor 4: Potential Water Savings
Water Savings // Alt. Water Systems
With low water landscapes implemented, how much water (non potable) could be provided by graywater and rainwater harvesting systems?
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Water Savings // Rainwater Harvesting
Low Water Pla...0
5001000150020002500300035004000
Average Monthly Water Demand: Low Water Plants
MaximumAverageMinimum
Gal
lons
/Mon
thFactor 4: Potential Water Savings
2,200 gallon cistern
January
February
March AprilMay
JuneJuly
August
September
October
November
December
00.5
11.5
22.5
33.5
4
Average Precipitation by Month, LA County
Inch
es
2.64 inches for 1,900 gallons
Sources: Pacific Institute, DWR, PPIC, US Census Bureau, LADWP
15
Water Savings // Graywater Systems
Annual Demand (DWR)
Annual Demand (PPIC)
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
Water Demand for Low Water Landscapes and Average Graywater System Supply Po-
tential
Lower Range
Upper Range
AF/
Y
Factor 4: Potential Water Savings
Average Annual Graywater Potential (6,500 AF/Y)
Sources: Pacific Institute, DWR, PPIC, US Census Bureau, LADWP
16
Water Smart Landscaping // Costs
Sources:
Factor 5: Cost of Saving Water
How much do low water landscapes cost in relation to turf, and are graywater, rainwater, microspray and drip systems economical?
17
Water Smart Landscaping // Costs
Factor 5: Cost of Saving Water
Water-efficient landscape
Turf landscape$0
$2,000
$4,000
$6,000
$8,000
$10,000
$12,000
$14,000
Labor/maint.Labor/maint.
Water
Water
Five-Year Upkeep Cost Compari-son: Water-Efficient vs. Turf
Landscapes*
Installing a water-efficient landscape comes with no upfront cost premium and results in substantial cost-savings over the long-term.
Sources: landscape contractor survey evidence, Home Depot Mulch Calculator, SNWA Xeriscape Conversion Study
18
Microspray and Drip Irrigation // Costs
Sources: emeraldlawnsprinklers.com, naturallandscapeandirrigation.com, hunterindustries.com
Factor 5: Cost of Saving Water
Sprinkler system Drip system Microspray system
Each system costs approx. $2-4/sq ft of installation.*
*According to landscape contractor survey evidence
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Alternative Water Supplies // Rainwater Harvesting // Costs
Factor 5: Cost of Saving Water
~$400
$2,600/AF*
~$1,300
$20,000+/AF*
110-GAL TANK
2200-GAL TANK
Sources: Hey!Tanks LA, Pacific Institute
High upfront cost + short wet season = low to no ROI* (however, rebates can increase cost-effectiveness)
*According to landscape contractor survey evidence
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Alternative Water Supplies // Graywater Systems // Costs
Source: Greywater Action, 2014
Factor 5: Cost of Saving Water
$250
$500
Laundry to LandscapeAverage Cost = $750*
$375
$1,000
$340
Branched DrainAverage Cost = $1,715*
$1,500
$2,000
$540
Pumped SystemAverage Cost = $4,040*
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Summary
Summary
• Waste or unreasonable use is a viable approach to addressing potable water used to irrigate residential landscaping in California.
• 12,922-14,799 AF/Y of potable water could be saved annually in California with new development using low water landscaping practices.
• 320,444-356,749 AF of potable water could be saved from 2015-2030 if new development uses low water landscaping practices.
• Graywater and rainwater systems can help address the remaining water need for low water plants, especially graywater systems.
• Installing low water landscapes comes with no upfront cost premiums and results in substantial savings over time.
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Questions?
Questions?
Source: NBCnews.com