Irrigation System Sustainability Improvements for Washington Park Arboretum’s Azalea Way

Azalea Way Irrigation project
Total Amount Awarded: $52,323

The Washington Park Arboretum (WPA) is an accessible, living laboratory and a portal to the University of Washington for both those affiliated and unaffiliated with the institution. Established in 1934, it is co-owned and managed by the University of Washington Botanic Gardens and the City of Seattle Parks and Recreation. Its extensive plant collections are known amongst its botanic garden and arboreta peers to be one of the top five in the nation. Over 250,000 visitors a year walk our 230 acres with binoculars, cameras or dog leashes in hand ready to explore and learn while simultaneously getting exercise and outdoor experiences.

Currently, our antiquated irrigation system contradicts the University of Washington’s sustainability goals, as it uses over five million gallons of water in a six month period. We believe this water use can be substantially decreased by updating the irrigation system in the Arboretum with newer systems that account for rainfall, temperature fluctuation, water loss through evaporation and transpiration, and soil moisture sensing. With the help of the Green Seed Fund we aim to hire an irrigation auditor to audit one of the oldest and historic sections of our irrigation system, Azalea Way. We also plan to use these funds to implement recommendations from the audit and replace two of three oldest controllers. We will also add water flow sensors to three controllers (two new and one old) to compare water usage between the updated system and the outdated controller. We expect this system upgrade to drastically reduce water consumption and irrigation labor hours on Azalea Way.

Designed by the famed Olmstead firm in 1939, Azalea Way is a high-traffic gateway into the 230 managed acres of rare, historically important and stunningly beautiful plants in the Washington Park Arboretum. Unfortunately, while it is beautiful above ground, behind the scenes lies an aging irrigation system that can be operated more efficiently with modernized controls and site condition sensor inputs.

As a University of Washington facility, the Arboretum is one of the most tangible faces that the UW presents to the public. A modernization of the antiquated irrigation system will be an excellent tool to educate and inform the public of the University’s level of environmental sustainability that we strive for on all our campuses. This large scale, system oriented project can be replicated on multiple UW campuses and can have lasting effects on purchasing, modernization, and installation of irrigation systems within the University and the entire Seattle Parks and Recreation (SPR) department. This unique partnership with SPR allows the funding of this grant proposal and subsequent results distribution to cast a much larger net within Seattle and the Puget Sound region than just within the University of Washington system.

Relevance to UW Sustainability Goals:

As stated on UW’s campus sustainability website, significant amounts of water are used for irrigation on all university lands, and UW has spent approximately $3 million on water conservation efforts since 2001, thus dramatic reductions in water consumption by the University have been achieved. However, this does not accurately reflect the water consumption at UW Seattle, because Seattle Parks and Recreation pays the water bill at the Arboretum, even though the University owns the plants being watered and UW employees maintain and operate this system. Therefore, no water usage in the 230 acre arboretum is included in these figures. Sadly, if the Arboretum were to be include in these figures, the impressive reductions might be substantially decreased. The Arboretum has already consumed over 5 million gallons of water in 2015 alone.

Our first specific goal of this project is to drastically reduce the amount of water the Washington Park Arboretum uses on the historic Azalea Way thereby helping the University of Washington reduce water consumption and achieve its sustainability goals. If successful this reduction of water use in 1/3 of the outdated irrigation areas in the Arboretum will have no negative effects on the plants in that area or the visitor’s experience in the Arboretum. Upon completion we will have the information needed to move forward with a proposal to the Seattle Parks Department that they implement water saving strategies in the remaining 2/3 of the Arboretum’s grounds.

In addition to water use reduction, this modernization will reduce the amount of irrigation labor hours on Azalea Way. This will be evaluated by reviewing daily time sheets from 2015 to document the amount of hours spent repairing or adjusting the irrigation controllers on Azalea Way. Time spent adjusting or repairing the new controllers and upgraded system in 2016 will also be documented and compared to 2015 to quantify the expected reduction of irrigation labor hours on Azalea Way.

A second goal of this project will be to educate the public on our effort to reduce our water consumption without negatively impacting the visitor experience. The Washington Park Arboretum hosts over 250,000 visitors every year, many of them current students, employees or alumni of the University of Washington. To continue with the University’s educational mission we plan to produce signs explaining the project, promote free classes to the public promoting water reduction strategies and how that can translate into their own gardens, and make a final project presentation open to the public. We will also work to educate park visitors regarding the University’s commitment to research on sustainability, the Green Seed Grant program, and how the public can help support and follow this endeavor.

An additional outcome of this research will be education of landscape professionals. The University of Washington Botanic Gardens plays a significant role in the education of local horticulturists, landscapers, arborist and groundskeepers. Through our professional continuing education program, ProHort, we plan to offer classes to these professionals to inform them of our results and how they can incorporate water saving strategies into their work.
As an educational leader and sustainability model, the University of Washington has the ability to be a living, learning laboratory to multiple groups visiting the Washington Park Arboretum. Our 230 acres is integral in the lives of students, landscape professionals, alumni, and tourists to name a few. Our research will be a highly visible example of the University of Washington’s commitment to sustainability and research in water conservation.


The time frame of this grant funding cycle is ideal for successful implementation of this project. Currently drained and winterized, our irrigation system will not be used again until late spring or even early summer. Any alterations or complications encountered during installation will not put stress on plants not receiving water, as they will not need supplemental water from the system at that time anyway.

This project will begin in February 2016. After the irrigation system is recharged with water staff will troubleshoot and perform obvious and minor repairs needed in preparation for the audit. We will then have a systems audit on the three controllers on Azalea Way and the valves, zones, and spray heads associated with those controllers. We will install new controllers and flow sensors and all required hardware and software for the new system in February, March and April to have the system tested and ready to go by May when we will likely have to begin watering the gardens.

We will run the system for the watering months of May through October gathering data about water usage, employee hours, and plant health. We will compare these new data with data from previous years as well as with data from the new flow sensor installed on the older controller monthly. Irrigation systems will be winterized in November, so all data collection will end in October 2015.

Primary Faculty:
Jon  Bakker
Primary Staff:
Kathleen DeMaria
Primary Student:
Ryan Garrison

This project was funded during the 2015-2016 academic year.