WATER CONSERVATION IN POMONA: FEASIBILITY OF XERISCAPING AND IRRIGATION IN POMONA’S PARKS
Water Conservation in Pomona: Feasibility of Xeriscaping and Irrigation in Pomona’s Parks
Alia Wilkinson
Cal Poly Pomona
June 2015
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Abstract
This paper explores ways in which the Southern Californian City of Pomona may save
water used for outside irrigation in parks in order to conserve natural and economic resources.
By replacing current varieties of plants in parks with varieties native to the Mediterranean
climate, as well as water conserving plants, this study originally postulated that Xeriscaping
Pomona’s Parks may support conservation goals. After careful analysis of costs of xeriscaping in
Pomona compared to available resources, this study concludes that Xeriscaping is cost
prohibitive in parks, and that more efficient conservation irrigation systems supported by state
subsidies would be more efficient in saving water, as well as monetary resources for the City of
Pomona.
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Drought in California
Climate Central, 2015
As of June 2015, California is in its fourth year of drought. The California State
Government makes weekly drought reports available online which describe shrinking well
levels, increased fires, public programs to increase reservoir levels, conservation of water, and
aide in event of a crisis (California Emergency Services, 2015). California legislators are
currently working with Australian conservationists who implemented solutions for water usage
during Australia’s “Big Drought,” which lasted from the late 1990s to 2012 (Gelineau &
Knickmeyer, 2015). These Australian conservation experts were able to create solutions in which
55 gallons of water a day for each Australian citizen became a comfortable norm. This number is
a stark contrast to the 105 gallons Californians currently use per day (Gelineau & Knickmeyer,
2015).
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One effective method used to conserve water is xeriscaping, or using a combination of
native and water conserving plants to reduce water consumption in human populated areas
(Brazel, Gober, Lee, Grossman-Clarke & Zehnder, 2007). This method also mitigates the effects
of an Urban Heat Island (UHI), which occurs in dry, hot urbanized climates where close
proximity of buildings leads to an increase in temperature, pollution, and discomfort (Brazel,
Gober, Lee, Grossman-Clarke & Zehnder, 2007). This essay examines whether xeriscaping
Pomona’s parks will be an effective method of conserving water and mitigating UHI in
Pomona’s urban environment.
Xeriscaping
Xeriscaping is a method of landscaping which reduces the need for irrigation (Denver
Water, 2015). It was originally conceived by Denver Water, a public utility which serves the
Denver, Colorado through water rates and tap fees instead of taxes (Denver Water, n.d.). Plants
are chosen for landscapes based off of a combination of water saving and native criteria.
Advantages of xeriscaping are conservation of water, reduced maintenance, retention of rain
water, and lower long term costs of maintaining land. Xeriscaping may also reduce waste and
pollution, as it eliminates caustic fertilizers and lawn clippings (Denver Water, n.d.).
Disadvantages include cultural interest as manicured grassy lawns are considered a sign of
prosperity, safety concerns from using cacti and agave which may have spiny exteriors, and
initial cost of the project (Denver Water, n.d.).
There are seven main design principles of Xeriscaping. They include: creation of an
initial plan, planting with amended (water retentive) soil or gravel, efficient irrigation methods in
which large water drops are used (with a hand held hose, for instance), selecting appropriate
vegetation, choosing a zone where plants will grow, the use of mulch to keep plant roots cool
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and delay evaporation, limit grasses, or plant with native grass varieties which require less water,
and maintain the finished landscape according to the plant types chosen (Denver Water, 2015).
The City of Pomona
Pomona, CA is the fifth largest city in Los Angeles County. It is located in the east
between the San Gabriel Valley and the Inland Empire (City of Pomona, n.d.). Most Los Angeles
natives know Pomona as the home of the Glass House and Fox Theater music venues, and the
fairground, which hosts events like the Los Angeles County Fair and Moon Block Party (City of
Pomona, n.d.). Home of the Tongva Native Americans, the city was overtaken by settlers in the
1930s and named for Pomona, the ancient goddess of Fruit. In the 1920s, Pomona had one of the
highest per capita income levels in the U.S.A, and was used as a test market for movie
previewing in the 1940s (City of Pomona, n.d.). Gang presence grew prevalent in the 1950s, with
crime spiking in the 1960s and 1970s (Profile of Pomona, n.d.). Movies made with gang crime
themes about Pomona perpetuated the perception that Pomona was impoverished and dangerous.
Despite a current per capita income of about $17,000.00 ($12,500 lower than California’s
average at about $29,500.00) and a crime index of about 400 points, 300 crime points higher
than the United States average per 100,000 people (U.S. Census Bureau, 2010), several
universities, a strong historical society, museums, and a vibrant community make Pomona a
colorful place to live (City Data, n.d.). Historic architecture including over 120 churches and
religious temples, as well as craftsman houses from the late 1800s, show the distinguished and
eclectic nature of Pomona (City Data, n.d.).
The city has a Mediterranean climate with hot summers and mild winters. Santa Ana
winds from the northeast seasonally lower the temperature and make the air dry (Profile for
Pomona, CA n.d.). According to the 2010 U.S. Census, Pomona has 149,058 people and is
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70.5% Hispanic or Latino, 12.4% White, 7.3% African American, 1.2% Native American, 8.5%
Asian, and 30% other races. The scale of the map below is 1:45,00:
Wilkinson, 2015
Pomona is home to 24 recreational parks which cover 13.2% of land in the city
(Wilkinson 2015). According to Antonio Karraa, Director of the Pomona Parks Department,
Main vegetation cover in the parks is combination blue grass and bermuda varieties. Flowering
shrubs and other types of grasses are plants native to wetter climates, though there is mixed use
of chaparral plants and succulents native to the area within the recreational parks. Some parks,
such as Lincoln Park, are landscaped with palm trees while others rely on deciduous trees for
canopy and shade (Karraa, personal communication, June 2015).
After interviewing Mr. Karraa, the Parks Department director, and extensively searching
public documents, a direct or official estimate of water consumption for Pomona’s Parks
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maintenance requirements were difficult to obtain. Pomona does, however, use rotating and
small spray sprinkler heads, which are known to conserve water. Pomona’s Parks Budget is
$1,942,173, which amounts to 0.08% of the City’s overall budget. This includes all line items,
including landscaping. Much of this number accounts for the salaries for the two people working
in the department, though Mr. Karraa did not disclose the exact line item usage of the budget.
Effects of Xeriscaping Parks in Pomona
The cost of xeriscaping varies widely depending on area of land and types of plants
desired, as well as maintenance of those plants (Medina & Gumper 2004). Water conserving
plants are only effective in if they are allowed to bolt, or flower, during the summer, which some
people find to be aesthetically displeasing (Medina & Gumper 2004). They also require an
efficient soil and water irrigation system in order to grow properly and save water.
It would be necessary for the Pomona Parks Department to allow xeriscaped vegetation
to flower and grow large leaves in the summer, despite the appearance of the bolted plants.
According to Tim Thomas at Install Direct, a landscaping company, Pomona’s parks would
require and upfront cost of $0.90 to $1.25, per square foot, based on which company was used
and what kind of contract the city could negotiate (Thomas, personal communication, June
2015). The area of Pomona’s parks at 88,525,369 square feet makes this upfront cost, on
average, about $88,525,369.00. In the desert, about 70% of water is used outdoors (City of
Scottsdale, AZ, n.d.). Xeriscaping could cut down this water usage by 1/3, but the cost for
xeriscaping all parks in Pomona at once is prohibitive (Karaa, personal communication, June
2015).
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A report by the Metro Water Conservation in Colorado, which is located in the Alpine
Tundra, performed a longitudinal study from 1997-2002. Xeriscaping was shown to yield an 1850% increase in water savings (Medina & Gumper 2004). Landscape changes alone, the study
concluded, typically only count for about one third of water savings. Another study by Dr.
Sylvan Addink, a professional agronomist at University of California, Riverside (UCR),
performed a cost analysis on “cash for grass” state subsidy programs for individual households to
xeriscape personal property in North Marin Water District, Albuquerque, New Mexico, El Paso,
Texas, and the Southern Nevada Water Authority (Addink, 2003). Addink’s findings concluded
that programs with improved irrigation systems, which required less water, were 2/3 more
successful than other programs, indicating that only 1/3 of the water savings came from
Xeriscaping. Using efficient irrigation alone can save 30-50% of water usage in an area (Addink,
2003).
Due to the exorbitant high cost of installing xeriscaping in the parks of Pomona, it would
not be advantageous to install this kind of landscaping. The Parks Department is already working
long term to replace non-native and water intensive varieties of plants piecemeal as is necessary
for the landscape in order to save water, according to Mr. Karraa. Carefully planned irrigation
systems would be much more cost effective for the city as a whole while conserving more water
than vegetation replacement would.
Options for Water Conservation
After analyzing water conservation studies performed in Mediterranean and Desert
Climates, it is postulated that irrigation systems are the most inexpensive and effective way to
conserve water in Pomona's Parks. SoCal Water Smart is a rebate program through the
Metropolitan Water District of Southern California and 26 member agencies which provides
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rebates for individuals and businesses who install water conserving appliances (SoCal Water
Smart, 2015). It is financed through the California State Fund. Outdoor landscaping subsidies
include weather based irrigation controllers, central computer irrigation controllers, rotating
spray nozzles retrofits, high efficiency large rotary nozzle retrofits, in-stem flow regulators, and
soil moisture sensors (SoCal Water Smart, 2015). Below is a table of subsidies for landscaping:
(SoCal Water Smart, 2015)
Using google.com to search prices in surrounding stores and averaging the top five prices
for different kinds of effective irrigation parts, this table was created to show how much money
the city of Pomona could save per part:
Wilkinson, 2015
According to Antonio Karraa, Parks Director, Pomona already uses rotating and small spray
sprinkler heads. It would be necessary to install the rest of the infrastructure to increase irrigation
effectiveness by about 30% (Karraa, personal communication, 2015).
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Pomona, compared to the rest of LA County and the Inland Empire, is rich in water.
According to Damien Martinez, Senior Management Water Analyst for the City of Pomona, coauthor of Annual Water Quality Report, 70% of the city’s water comes from ground water wells
throughout Pomona and Claremont (Martinez, personal communication, June 2015). Three main
local naturally occurring aquifers provide much of this water, with the largest aquifer located in
Chino. Melted snow from the San Gabriel Mountains provide 5% of Pomona’s water. The
Metropolitan Water District state project provides 25% through water wholesale. This is the most
expensive option, as much of the water has to be imported from Northern California, and is
usually of lower quality, according to the Annual Water Quality Report. According to Mr.
Martinez, other cities, like Walnut, must import upwards of 90% of their water, while Pomona
has its own groundwater as well as five of its own treatment plants. These water sources make
water in the City of Pomona cleaner, and less expensive than water in surrounding areas.
Pomona’s plentiful water sources decrease costs, and the city continues to strive to stay as
sustainable as possible when consuming water (Martinez, personal communication, June 2015).
According to Mr. Martinez of the water department, Pomona uses 22,500-23,000 acre
feet per year of water. If 70% of this water is used in irrigating outdoor areas, irrigating parks
would take about 16,100 acre feet of water per year. If proper irrigation saved 30% of water in
Pomona from this portion, 4,800 acre feet of water could be conserved. This would amount to
156,4087,000 gallons of water saved each year.
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Martinez, personal communication, 2015
Inside the city limits, water costs $.94 per unit, or 100 cubic feet of water. If Pomona uses
22,550 acre feet per year, this amounts to about 982,278,010 cubic feet of water, converting to
9,822,780 units per year. At $.94 per unit, Pomona spends about $9,233,413.20 on water. If the
City of Pomona could save 4,800 acre feet, or 209,088,002 cubic feet to prevent the use of
2,090,880 units per year, the city could save $1,965,427.22 per year with water conserving
irrigation installed in Pomona’s Parks. Elena Yates of the Parks Department was unable to give
an estimate of how much irrigation infrastructure would cost to install in the parks (Yates,
personal communication, June 2015).
In lieu of an official estimate, it may be estimated that, with the cost of the new irrigation
infrastructure achieved by adding together the irrigation items in the SoCal Water Smart
irrigation subsidy guide minus low flow nozzle sprinkler heads, which Pomona’s Parks already
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have, each park may require $10 per acre for installation of irrigation infrastructure (estimated
from cost of nozzles and controllers needing replacement), where the parks cover 2,032.26 acres
of Pomona. Two thousand work hours for installation at $15 per hour would be necessary to
install this infrastructure. Together, these estimates would cost the city $50,322.60 to install
water conserving irrigation in the parks. This is well worth the estimated $1,910,104.62 saved
through water conservation which would result from this effort in the first year of its successful
installation.
Conclusion
Xeriscaping the whole of Pomona’s parks, currently, would be cost prohibitive. Plant
varieties of exorbitant water need are currently are being replaced methodically and over time
with native and water conserving species of grass and succulents without spines by the Pomona
Parks Department. Efficient irrigation systems should replace older and inefficient ones in order
to save the city 30-50% of water currently being used to water parks. Water savings from
decreasing outdoor water use by 30% would result in water savings of $1,965,427.22 per year
with an initial estimated cost of $50,322.60 for installation of irrigation systems, saving the City
of Pomona $1,910,104.62 in water costs in the first year alone. A government grant, money from
the state, federal, or city funds may be necessary for the initial cost of installation, but economic
and natural resources saved through proper irrigation would save the City much money in the
long run. A more extensive study when irrigation has been installed and plant varieties have been
replaced should be performed to determine effects of vegetation choice pertaining to the Urban
Heat Island effect.
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References
Xeriscape Plans. (n.d.). Retrieved May 16, 2015, from
http://www.denverwater.org/Conservation/Xeriscape/XeriscapePlans/
McKenney, C., & Terry Jr., R. (1995). The Effectiveness of Using Workshops to Change
Audience Perception of and Attutudes About Xeriscaping. HortTechnology, 327-329.
Retrieved May 19, 2015, from
http://horttech.ashspublications.org/content/5/4/327.full.pdf html
Gelineau, K., & Knickmeyer, E. (2015, May 25). California looks Down Under for drought
advice. Alternative Press, p. 2.
Climate Central (2015). California Drought. Retrieved May, 25, 2015 from:
http://images.mic.com/hvqekow2qrtwo1uskusmum0g1ybeo758pkjoiuyayow0d8hynzptmi
k8ihao9ecu.jpg
California Governor’s Office of Emergency Services (2015). Drought Update Tuesday, June 2,
2015. Sacramento, CA: U.S. Retrieved June 3, 2015.
City of Pomona - About Pomona. (n.d.). Retrieved June 2, 2015, from
http://www.ci.pomona.ca.us/index.php/about/about-pomona
Profile for Pomona, California, CA. (n.d.). Retrieved June 3, 2015, from
http://www.epodunk.com/cgi-bin/genInfo.php?locIndex=10716
2010 Census Interactive Population Search. (2010). Retrieved May 24, 2015.
Crime rate in Pomona, California (CA). City-Crime.com (2015, June 1). Retrieved June 3, 2015.
Scottsdale Xeriscape Garden at Chaparral Park. ScottsdaleAZ.Gov. (n.d.). Retrieved June 4,
2015.
Brazel, A. , Gober, P. , Lee, S. , Grossman-Clarke, S. , Zehnder, J. , et al. (2007). Determinants
of changes in the regional urban heat island in metropolitan phoenix (Arizona, USA)
between 1990 and 2004. Climate Research, 33(2), 171-182.
Medina, J., & Gumper, J. (2004). Yield and Reliability Demonstrated in Xeriscaping. YARDX,
1-8. Retrieved June 3, 2015, from
http://coloradowaterwise.org/Resources/Documents/YARDX_Report.pdf
Addink, S. (2003). “CASH FOR GRASS” - A COST EFFECTIVE METHOD TO CONSERVE
LANDSCAPE WATER? 1-14. University of California, Riverside.
SoCal Water Smart (2015). “Soil Moisture Sensor Qualifying Products List.” The Metropolitan
Water District of Southern California. Retrieved July 3, 2015.
Lowry, L., Chamberlain, P. Pomona Public Financing Authority Staff Report (2014). The Public
Financing Authority of the City of Pomona. Pomona, CA. Retrieved June 3, 2015.
Wilkinson, A (2015). “Map of Pomona’s Parks.” Cal Poly Pomona, GIS Lab. Pomona, CA.
Created June 1, 2015.
WATER CONSERVATION IN POMONA: FEASIBILITY OF XERISCAPING AND IRRIGATION IN POMONA’S PARKS
Wilkinson, A (2015). “Table of Potential Savings From Irrigation Subsidies for Pomona.”
Created June 3, 2015.
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