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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?

14

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

19

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.

22

Questions?

Questions?

Source: NBCnews.com