season runoff. The study also sought to gauge consumer acceptance of controllers as a means of
water management. This 18-month study in Irvine, CA, involved five similar neighborhoods,
each having its own single point of discharge into the urban storm drain system. Runoff volume
was monitored and water quality samples collected at the points of discharge. The five sites were
divided into three study areas. The first area, representing the retrofit group, received ET
controllers and public education. The second area received educational materials but no
controllers. The third study area, the control group, contained three neighborhoods that received
neither ET controllers nor educational materials. This was one of the first studies to attempt to
quantify the effectiveness of public education alone versus a technology-based plus education
approach in reducing residential irrigation water use.
In the retrofit group, 72% of participants indicated they were satisfied with the WBIC's
performance, which either maintained or improved landscape appearance. Data show households
accepted the controller as a method of saving water, reducing runoff, and watering their
landscape. The study found that twice the number of retrofit households observed a decrease in
their water bills than did education-only households. However, 58% of retrofit households said
they would not be willing to pay for an ET signal (the study calculated the controller cost and
annual signal fee at $198 per year and water savings at $168 per year). In terms of water savings
per controller (and cost-effectiveness), the study indicated that larger landscape areas (parks and
street medians) represent the best initial targets for similar programs.
2.3.32 Evaluation of Weather-Sensing Landscape Irrigation Controllers, January
through December 2003
By D.R. Pittenger, D.A. Shaw, and W.E. Richie.
Submitted to the Office of Water Use Efficiency, California DWE, by the
University of California Cooperative Extension, Center for Landscape and
Urban Horticulture. 25 pages.
The study reported on in this document examined irrigation controllers that adjust water
application in response to ETo or other environmental parameters. The study aimed to provide a
scientific analysis of the ability of such controllers to meet plant water demands. In 2003, the
authors evaluated weather-sensing irrigation controllers to determine what climatic data the
controllers utilize, how easy they are to set up and operate, and how closely their irrigation
systems match landscape needs. The authors studied Aqua Conserve ET-6, WeatherSet WS16,
WeatherTRAK, and Calsense ET1 incorporating an electronic ET gauge. The manufacturer’s
directions were followed in programming stations on each controller to schedule irrigation
automatically from January through December 2003. The authors tested controllers on the
following hypothetical landscape plantings: cool-season turfgrass, trees/shrubs, annual flowers,
mixed high water use plants, and mixed low water use plants. The following points are major
conclusions from the study.
• Greater complexity and technicality of setup does not necessarily result in more accurate,
water-conserving irrigation schedules.
• Adoption of Smart Water Application Technologies will not eliminate the need for
human involvement in managing landscape irrigation.
• Weather-sensing controllers generally require professional monitoring and follow-up
adjustment of their initial settings.
• Use of weather-sensing controllers does not assure landscape water conservation or
acceptable landscape plant performance.
The study summarizes the performance of each controller. They found Aqua Conserve to be the
“most appropriate for homeowner use,” but ultimately concluded that no product was able to
produce highly accurate irrigation schedules consistently for every landscape setting when
compared to reference treatments used in a research setting.
2.3.33 Santa Barbara County ET Controller Distribution and Installation Program
By HydroPoint Data Systems, Inc.
June 30, 2003.
Six water agencies near Santa Barbara, CA, developed the Santa Barbara County ET Controller
Distribution and Installation Program, which in May 2001 received funding from a Water Use
Efficiency Grant through the CALFED Bay Delta Program. The program chose to install the
WeatherTRAK ET controller based on the Irvine Ranch Water District's positive experience with
the device. Throughout the 2-year study, program staff did significant planning, organizing,
educating, and outreach to make the program a success. Starting in July 2002, the program began
utilizing Hydropoint's Data Systems Customer Service and worked with Hydropoint to present
installation training workshops. The county planned to distribute 300 ET controllers with rain
sensors and soil probes at no cost to participating customers. To encourage customer buy-in,
participants had to pay Hydropoint Data Services 3 years' worth of signal fees when they joined
the program (a total of $144 billed at $4/month).
Costs associated with the program included the cost of controllers ($200 each);
installation fees ($100 to $150); soil probes ($12 each); and consultant fees for marketing
assistance, training workshops, and customer service (all paid for through grant funding).Two
installer training workshops and one training lab were held to develop a list of trained installers
for the program. HydroPoint reports that initial data indicate an average overall savings in water
use of 26%, with a highest overall water savings of 59% and lowest of 8%. Using the factory
settings for precipitation rates in the WeatherTRAK controllers did not result in reliable savings.
2.3.34 Final Report—Evaluation of a Soil Moisture Sensor to Reduce Water and
Nutrient Leaching in Turf
By S.M. Pathan, L. Barton, and T.D. Colmer.
Horticulture Australia Project number TU 02006. 23 pages.
This research project, funded by Horticulture Australia Limited and Holman Industries,
evaluated the Holman soil moisture sensor, WaterSmart™. Experiments were conducted for 12
months at the field facilities of the University of Western Australia and the nearby public
Lanchester Park. Irrigation water was applied to turf plots either as recommended by the Western
Australia Water Corporation (in periods of no watering restrictions), or when indicated by the
soil moisture sensors (SMSs).
In summer the total volume of water applied to turfgrass plots controlled by the
WaterSmart SMSs was 25% less than the volume applied based on the water corporation's best-
practice watering schedule. Results were similar for the test site in Lancaster Park. Between late
spring and early autumn (October 2002–April 2003), the volume of water applied to SMS-
controlled plots was 34% less than at plots subject to conventional scheduling. Three replicates
were tested. Turf quality was maintained at acceptable levels throughout the study.
2.3.35 Residential Landscape Irrigation Study Using Aqua ET Controllers
By S. Addink and T. W. Rodda.
Denver Water, Denver, CO; City of Sonoma, CA; and Valley of the Moon
Water District, CA.
The effectiveness of Aqua ET controllers for residential landscape irrigation was evaluated in
Denver, CO, and in two water districts in Northern California during 2001. Water usage data for
74 residences was collected during the 2001 irrigation season. The data were analyzed to
determine outdoor water savings resulting from the use of weather based Aqua Conserve
controllers provided and installed by the manufacturer. The data collected from the studies
indicated that participants experienced a total outdoor water savings of 21%, 23%, and 28% in
Denver, City of Sonoma, and Valley of the Moon Water District, respectively. Total savings of
7.64 acre-feet are reported, with average savings for individual residences ranging from 7% to
25% for the three study areas.
2.3.36 Water Efficient Irrigation Study: Final Report
By the Saving Water Partnership.
This report describes a study conducted in Seattle in 2002 to examine water savings and
customer satisfaction related to (1) WBICs with or without rain sensors, (2) hardwired and
wireless rain sensors, and (3) an irrigation scheduling service. The study sought participants who
demonstrated historically high water usage, especially during the peak season. During the peak
season, the participants historically used an average of 375 gal/day above daily winter use. Aqua
Conserve controllers were installed in 35 high-usage residential sites. Twenty installations
included rain sensors; 15 used a controller only. Water savings were calculated relative to
historical consumption during 1998 and 2001, adjusting for weather conditions. The water
savings were 20,735 gallons per year for each site that had a controller plus rain sensor, and
10,071 gallons per year for each site that had a controller only. Most participants reported
satisfaction with controller performance, although many said the devices were difficult to
operate. Because precipitation rates during the study were only 53% of the historical average, the
study period was not the best for testing rain sensors. A theoretical analysis, however, indicated
that rain sensors potentially could reduce watering by 20%.
2.3.37 Report on Performance of ET-Based Irrigation Controller: Analysis of
Operation of WeatherTRAK™ Controller in Field Conditions During 2002
By Aquacraft, Inc.
Prepared for the Cities of Boulder, Greeley, and Longmont, CO. 23 pages.
Residents of Boulder, Longmont, and Greeley, CO, participated in a 3-year field study (2000–
2002) of the WeatherTRAK™ irrigation controller. The goal was to determine whether (1) the
controller functioned reliably, and (2) the system could match water applications accurately to
ETo. Pager technology connected the ET-based controllers to local weather stations. Signals sent
periodically to each controller adjusted the irrigation schedule to provide the appropriate amount
of water for the plant types in each zone. In 2002 seven of the nine study participants were
single-family residences. WeatherTRAK decreased irrigation from an average of 34.4 inches
applied in 1998–2000 to an average of 27.2 inches—a 21% reduction. The seven sites saved an
average 35,000 gallons of water each compared to their historical water use. The four
participants who saved the most averaged annual savings of 64,000 gallons, showing the great
savings potential for programs focused on high water users. The study concluded that the
WeatherTRAK system performed well and was capable of translating ET data into irrigation
schedules, adjusting for drought measures when necessary.
2.3.38 Irvine Ranch Water District's Application of Signal Paging to ET Controllers
for Medium-Size Commercial Landscapes
By T. Hunt and N. Mrvos, Irvine Ranch Water District (IRWD).
*Abstract only, obtained through search of the Irrigation Association website.
The IRWD found that WBICs are capable of supporting good water management. In its
Residential Run-off Reduction (R3) study, IRWD replaced 112 residential irrigation controllers
with weather-based controllers that used a combination of local (at the controller) programming
and weekly remote schedule adjustments based on changes in ET. A remote operator sent a pager
signal to adjust the schedule in response to rain, heat, cloud cover, or high wind. The R3 study
took place in a residential setting that included parks, streetscapes, and condominiums,
landscapes typically viewed as commercial sites or medium-sized landscapes (MSL). This report
defines a MSL as 0.14 to 2 acres. The authors concluded that the most effective water
conservation can occur at MSL sites.
2.3.39 Performance Evaluation of WeatherTRAK
Irrigation Controllers in Colorado
By Aquacraft, Inc.
Study began in 2000; testing performed in 2001.
15 pages plus appendix.
This report describes a successful field test of WeatherTRAK ™ ET-based irrigation controllers,
which link via pager technology to a network of local weather stations. The field study took
place in Boulder, Longmont, and Greeley, CO. Ten sites were selected— nine residential and
one office—a combination of volunteers and high water-using accounts. The irrigation water
applied by each system were tracked and compared to the theoretical ETo requirements for the
Overall, the 10 sites saved an average of 26,000 gallons of water each compared to their
historical usage. Including only the five participants who saved significant amounts of water
results in an average annual savings of 68,000 gallons per site, indicating the large savings
potential of programs targeting major users. based on the authors' calculations, the
WeatherTRAK system appeared to capture about 88% of the potential savings on the 10 sites
The WeatherTRAK system also appeared to perform well technically, providing a reasonably
good translation of the ET data into irrigation schedules. Most users liked the system and
appreciated its ability to make adjustments automatically, but a couple of people considered the
system to be less flexible than it could have been. Although only one customer indicated a
willingness to pay for the system, most said they would adopt it if the utility paid for it.
2.3.40 Residential Weather-Based Irrigation Scheduling: Evidence from the Irvine “ET
By representatives of the Irvine Ranch Water District, Municipal Water
District of Orange County, and the Metropolitan Water District of Southern
California, plus various consultants.
This study field-tested a reasonably priced prototype ET controller that adjusts irrigation in
response to weather data received via a broadcast signal. Despite targeting high water users, the
study attracted households that already were interested in water conservation, making the
conservation potential relatively low. The ET controllers were able to convert almost 85% of the
pre-retrofit conservation potential into achieved savings, however. The controllers reduced total
water consumption by about 37 gallons per household per day, representing a 7% reduction in
total household use, or roughly a 16% reduction in outdoor use.
2.3.41 Soil Moisture Sensors for Urban Landscape Irrigation: Effectiveness and
By R.J. Qualls, J.M. Scott, and W.B. DeOreo.
Journal of the American Water Resources Association, Vol. 37, No. 3, pages
The study described here involved 23 test sites, all of which had sensors that were installed at
least 3 years previously during earlier studies. The field durability of the systems exceeded
expectations: all the granular matrix sensors (GMS) in contact with the ground remained
functional and required no replacement. One sensor was located in a city park and 1 in a traffic
median; 4 were on residential properties; and the other 17 were installed in two residential
communities maintained by two landscape contractors.
The authors compare the amount of water allowed by the sensors to the irrigation
requirement based on net evapotranspiration (ETN), which is the amount of water in excess of
rainfall that vegetation requires to satisfy its metabolic requirements. To measure ET, the authors
relied on the Soil Conservation Service's 1970 modification of the Blaney-Criddle (1952, 1960)
equation, which relates ET to mean monthly temperature and daylight hours, with corrections for
The study found that the soil moisture sensors successfully reduced water applications
during rainfall. The systems reduced irrigation applications well below theoretical requirements,
and tracked ETN well. Maintenance and repair costs were minimal, as was the time required to
adjust and operate the systems.
2.3.42 Demonstration of Potential for Residential Water Savings Using a Soil Moisture
Controlled Irrigation Monitor: Project Completion Report
By R.G. Allen, Dept. Biological and Irrigation Engineering, Utah State Univ.
U.S. Bureau of Reclamation Provo, Utah Office, Project 6-FC-40-19490.
This 1-year project demonstrated a then-new technology for helping residential users conserve
irrigation water. For the 1996 irrigation season, small electronic soil water control systems were
installed in residential sprinkler systems in two Utah cities. The WaterWatcher system, an
electronic control unit made by Turf Tech, was installed in-line between a resident's irrigation
clock and valves. The control unit automatically disrupted voltage signals to the valves whenever
the soil was wet. Twenty-eight units were installed in Providence and 9 in Salt Lake City. Of
those 37, 27 provided water use data of sufficient quality and completeness to enable comparison
with data from prior years. Compared to prior years, the 27 residences used an average of 10%
less water during the 1996 season than did the control group. Twenty-eight of 36 users said they
were impressed by the system’s simplicity, automation, and lack of maintenance. The authors
found no statistically significant differences in water use patterns or savings between the two
cities, indicating that the cost of water (which was higher in Providence) did not affect the degree
2.3.43 Performance of Soil Moisture Sensors During Field Operations: Update
By Aquacraft, Inc.
This report updates a study Aquacraft performed in1994 (reference 2.3.44). The update was
performed partly because the irrigation industry continued to express reluctance to use the SMS
technology. Working with the City of Boulder, CO, Aquacraft tested Watermark soil moisture
sensors and Watermark electronic modules for single- and multi-family residences, commercial
sites, and urban parks. Aquacraft evaluated system performance, including the ability to match
irrigation to requirements, after the systems had operated for several years in the field. Aquacraft
found that, with minor exceptions the devices effectively controlled automatic irrigation systems
and limited application rates to ET. The authors found that the time and cost of maintaining and
operating the systems were minimal; the systems remained reliable after several years.
2.3.44 Performance of Soil Moisture Sensors During Two Years of Field Operations
By Aquacraft Water Engineering.
This report adds a second year of data to the information Aquacraft reported in December 1993.
One goal was to enable a detailed comparison of water application verses demand in SMS
systems. The second goal was to distribute as many sensors to contractors and homeowners as
practical to discover whether, with limited input from the project team, laymen could install and
operate the devices properly.
Data on water use, rainfall, and temperature were collected during the 1993 and 1994
irrigation seasons to estimate daily ETN using the Blaney Criddle procedure. Then the Aquacraft
could compare the theoretical irrigation requirement (based on ETN, irrigation efficiency, and
soil moisture capacity) to applied irrigation water. Not only did the soil moisture sensors reduce
water use compared to the control group, but they managed to limit irrigation to levels well
below the theoretical ET requirements.
2.4 Evaluation and Testing
The following resources represent efforts to test or standardize smart controllers or to evaluate
their overall performance in actual use. Several studies listed under controller water savings
review other aspects of controller performance, such as irrigation adequacy and turfgrass quality.
Those studies are not repeated here.
2.4.1 Innovative Conservation Program (ICP)
By the Metropolitan Water District of Southern California.
Projects started in 2011 and completed in June 2013.
Metropolitan's ICP, in cooperation with the U.S. Bureau of Reclamation, funds research that
documents the water savings and reliability of innovative water-saving devices, technologies,
and strategies. New projects are chosen every other year. The 2011 program focused on
landscape irrigation and commercial, institutional, and industrial water use efficiency. One
project was titled, "Evaluate water savings from Cyber-Rain’s XCI Cloud irrigation controller at
12 commercial sites.” Real-time web-based irrigation water use data based on local tiered water
rates was to be used to motivate and evaluate customer conservation. The project, performed by
Cyber-Rain, Inc., was to be completed by June 2013.
2.4.2 Evaluation of Smart Irrigation Controllers: Year 2012 Results
By C. Swanson and G. Fipps.
Funded by the Texas Water Resources Institute, Technical report TR-443.
This report summarizes the evaluation of smart controller performance during 2012. In 2008
Texas A&M University at College Station established a facility for testing controllers from the
point of view of an end user (that is, a landscape or irrigation professional). Controllers were
tested using a Texas virtual landscape, which comprised 6 zones having varying plant materials,
soil types and depths, and precipitation rates. For 2012 nine controllers were evaluated for 216
days, from April 30 to December 2. Controller performance was analyzed for both the summer
and fall seasons. Controller performance was compared to irrigation recommendation of the
TexasET Network and website. Testing also sought to identify controllers that applied excessive
or inadequate amounts of water.
The report notes that programming smart controllers for individual site conditions
continues to be difficult. Only two of the nine controllers could be programmed directly with all
the parameters needed to define each zone. ET values recorded off the controllers were
inconsistent throughout the study, often greater than 150% of ET from the TexasET Network
2.4.3 Long Term Expanding-Disk Rain Sensor Accuracy
By L. Meeks, M. Dukes, K. Migliaccio, and B. Cardenas-Lailhacar.
Journal of Irrigation and Drainage Engineering, Vol. 138, No. 1, pages 16–20.
Throughout almost 5 years, researchers evaluated the accuracy of expanding-disk rain sensors.
Researchers evaluated seven combinations of rain sensor model and rainfall setpoint: the
Wireless Rain-Clik (WL) rain sensor; Mini-Clik (MC) rain sensors with rainfall setpoints of 3, 6,
6, and 13 mm (3MC, 6MC, Hunter, and 13MC); Irritrol RFS 1000 at a 6 mm setpoint (Irritrol);
and Toro TWRS at a 6 mm set point. The WL and MC configurations plus four replicates were
studied for 1,182 days. The Hunter, Irritrol, and Toro configurations plus eight replicates were
monitored for 1,150 days. The authors collected data to determine the total time each
configuration spent in interrupt mode and to compare those results with rainfall measured on site.
The authors conclude that for the most accurate and consistent behavior, Hunter Mini-Clik and
Hunter Wireless Rain-Clik rain sensors should be replaced after 1 year; Irritrol RSF 1000 and
Toro TWRS rain sensors do not require replacement for at least 3 years. Rain sensors could
increase water savings to homeowners and have environmental benefits but should not be used in
applications requiring an accuracy consistently greater than 70%.
2.4.4 Smart Water Application Technologies: 2012 Update
By B.E. Vinchesi, Chairman, Irrigation Association Smart Water Application
Technology Committee and Standards and Codes Committee.
Presented at the WaterSmart Innovations Conference, 2012. 26 slides.
The author presented slides to describe the status of smart water application technology (SWAT)
as of 2012. He reviewed the history of and participants in the development of SWAT testing. At
the time the Irrigation Association was developing testing protocols for high-uniformity sprinkler
nozzles and check valves. Both draft protocols were open for public comment. A technology to
be evaluated next is system interruption devices.
2.4.5 Examination of SWAT Protocol Utilizing a Performance Analysis of Weather-
Based Irrigation Controllers: Update with Extended Data
By M.D. Dukes and S. Davis, Univ. of Florida.
Submitted to Eastern Research Group (ERG) under ERG Project 0264.01.005;
UF Project 000 898 65. 48 pages.
The objective of this report was to analyze the effects of variable weather conditions on
performance of the SWAT test. SWAT tests were performed in Florida on three brands of ET
controller. The controllers—two signal-based systems and one stand-alone controller—had been
tested previously under the SWAT protocol. For this study, controllers were evaluated under a
range of weather conditions, such as frequent/infrequent rainfall and high/low ETo. The
controllers met the proposed minimum threshold of 80% for irrigation adequacy, but throughout
the study generally failed to meet the threshold of 95% for scheduling efficiency based on the
minimum score for the six zones established for SWAT testing. Over-irrigation was a frequent
issue. The study also found that, in general, the addition of a rain sensor increased or did not
affect the SWAT scores.
2.4.6 Maximizing Effective Agronomics in Landscapes with Soil Moisture Sensors
By J.J. Peters, American Society of Agronomy.
Irrigation Show, San Antonio, TX, December 2–4, 2009,.
This presentation reviewed the information needed to make agronomically sound irrigation
decisions, including the consideration of soil type, soil water-holding characteristics, and plant
water requirements. The presenter discussed optimal water management and described the
benefits and challenges of making irrigation decisions based on weather-based or soil moisture-
based systems. The capabilities of soil moisture-based irrigation controls were discussed,
including long-term performance, control, and effectiveness. The presenter reviewed the
performance of various techniques for measuring soil moisture and summarized the agronomic
benefits of smart watering approaches.
2.4.7 Examination of SWAT Protocol Utilizing a Performance Analysis of Weather-
Based Irrigation Controllers: Final Report
By M.D. Dukes and S. Davis, Univ. of Florida.
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