Water: A Conversation With Chandler Councilmember Rick Heumann

By Warren Tenney

When City of Chandler Councilmember Rick Heumann joined the AMWUA Board of Directors six years ago he knew this about water: “I drank it.” He knew Chandler had a water treatment plant and a wastewater treatment plant – and that he had been assigned to the board of an important regional water agency. When it came to water management, Mr. Heumann called himself a blank slate – but he wasn’t really. The business executive arrived on the AMWUA board without much water knowledge but with two convictions that make up the core of water management: you need a plan today to reach your goals in 20 or 30 years and successful plans require collaboration. Mr. Heumann also had insights gained from 20 years of community service, including sitting on Chandler’s Planning and Zoning Commission and Parks and Recreation Commission. The Councilmember, who ended up serving as president of the AMWUA Board, will attend his last meeting in December, so we sat down and talked to him about water.

The Surprises: Mr. Heumann worked to understand the complexities of the Central Arizona Project, the 360-mile canal that brings Colorado River water to the Phoenix Metro area and Tucson. He had to learn about the condition of the nation’s largest reservoir known as Lake Mead, the laws that allowed cities, Native American communities and small-heumannfarmers to share Colorado River water, the debt owed to the federal government for building the canal, and the energy needed from the coal-burning Navajo Generating Station (NGS) to lift the water uphill. “Why do you need all that power?” was Mr. Heumann’s first thought. “Just stick the canal there and it will flow down hill over hundreds of miles,” he now recalls. “Well, it’s not downhill it’s uphill, too. NGS is where the power comes from.” Mr. Heumann knows the NGS has been under scrutiny by the Environmental Protection Agency, but without it delivery of Colorado River water would stop. “You just can’t shut it down. You can’t build enough solar power to generate the power to move water uphill. But what’s the comprehensive approach over the next ten years?  Maybe we can use less of NGS, reduce the need for that by using wind, or nuclear, or solar or clean coal.”

The Big Question: There is one question about water that Councilmember Heumann gets most often: Are we going to run out of water? “When I talk about water, whether it’s a council meeting, a subcommittee meeting or chamber meeting, that’s one of the big things that come up. People read snippets and little tidbits of things and hear all the doom and gloom.” Mr. Heumann said there are two things people need to know: “One is that there is not an abundance of water, but there’s enough water if we use it right.” Small things people do add up, even if it’s not letting the water run when brushing your teeth or shaving or using a broom instead of a hose to regularly clean your driveway or patio. “It’s a restaurant not serving water unless you ask for water. How much does that save? Well, you know what, that glass of water may be 8 ounces, but if your restaurant serves 200 people a day that’s 1,600 ounces. Think how many gallons were wasted. Of those 200 customers, did 50 of them drink it? That’s 150 people you didn’t serve water to and all the dishwashing that goes along with it. So you start doing those incremental things.”



The Progress: Councilmember Heumann is well aware it will take more than incremental conservation for Arizona to have enough water to thrive. He helped Chandler to become the first city in the state to pass a policy that ties land use to the city’s 100-year water supply. Here’s how it works: If Chandler residents benefit from a new high-water-use commercial development, such as providing a lot of jobs, the City will provide the new development with water. If a development uses a great deal of water but provides only a few jobs, such as a data center, it must buy its water on the open market. The policy’s goal is to ensure that once Chandler’s entire available land is developed, the last people to buy homes or build businesses still will have a 100-year supply of water. “Some people get offended and say, ‘You should let people do whatever they want.’ Well, no. Chandler has 64 square miles. When that last guy wants to build his subdivision or his business he has to have that water.” Mr. Heumann has only one regret about the policy: It should have been in place 20 years ago. “What I hope is that cities like Goodyear and Gila Bend and Buckeye, high-growth cities, like Gilbert, that they really take a look at this policy. Because it’s not a policy designed to say you can’t have water. It’s a policy designed to say we’ve allocated our water resources, we know how much we have now, we know our 100 year supply.”

The Future: In the six years Mr. Heumann has been on the AMWUA Board he has watched AMWUA’s role change. “It has changed and should change to really a marketing arm.  I think it’s really important our cities are educating our citizens about conservation, on the right way to use water, where it comes from, thinking for the long term. Your grandkids are going to live here. Are they going to live here in a sustainable manner?” He wants to see the successful water management practices developed by AMWUA cities shared with non-member cities, such as Prescott and Payson. Mr. Heumann also sees a need for AMWUA and others to educate members of the Arizona Legislature about water so they know how to balance the state’s water resources with demands for new development, particularly on the outskirts of the Valley and in rural areas where water tables are dropping from over pumping from too many wells. “The Legislature needs to understand we (AMWUA) represent 3.5 million people. This is about sustainability, so my kids and grandkids will be able to live here. The legislators need to get out in the water to fully understand what really drives the lifeblood of the valley and understand it isn’t just about what we do today. What we do today affects us long term. You’ve got to think about a plan.”

For 47 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.

The Art and Efficiency of Fountains in the Desert

By Warren Tenney

Water is life and nowhere is that more apparent than in the desert. Fountains and pools of water were built into ancient cities, including desert cities, for both practical and aesthetic reasons. They provided access to water for human needs, to support livestock, to grow food crops and gardens. Water features also cool the air creating microclimates and mitigating noise. They allow city dwellers to experience the relaxing charm of moving water that make fountains natural gathering places. They connect people to a precious, shared resource that is often not top of mind in our modern world.

Our desert cities work to strike a balance between the beauty and practicality of fountains. The City of Scottsdale continually weighs people’s attraction to fountains against the need to conserve water and control the cost of energy and maintenance that fountains demand. The city has 21 decorative fountains, down from the 32 the city maintained before 2008. Scottsdale has removed eight and shut off the water to three. Scottsdale has saved an estimated 830,000 gallons of water a year by initiating these changes to its fountains.

Here are some of the ways Scottsdale has been able to maintain its most enjoyed water features.


  • In 1999, the City of Scottsdale began installing small water meters on every fountain. The meters allow the city to monitor water use, immediately find leaks and determine overflow. This sub-metering also helps the city to estimate how much water a proposed fountain would demand before approving it.
  • Nearly 100,000 people gather annually near the fountains and lagoon in front Scottsdale’s Civic Center Mall to enjoy festivals and concerts. The Mall’s 7-foot deep lagoon was an enthralling water feature with fish and swans, but it used a great deal of water and was difficult to maintain.  In 2008, the city raised the lagoon to a depth of 3.5 feet, reducing the volume of water it held by 550,000 gallons, and added a filtration and automated treatment system to the water feature to reduce maintenance.
  • Every fountain in Scottsdale now has a filter and automated treatment system, similar to systems used in commercial swimming pools. An employee regularly skims and cleans the fountains using portable and automatic vacuums, reducing the number of times the filter needs to be backwashed and saving water. In the past, backwashing happened every week, but now the city backwashes fountain filters only when needed. The added benefit: A partially dirty filter traps smaller suspended particles creating clearer water for the fountain. The employee who cleans the fountains uses brooms and leaf blowers to clean around the fountains instead of a hose.
  • Fountains that once flowed 24 hours a day now flow only when buildings and plazas are open and people can enjoy them. This saves water used, water lost to evaporation and electricity. (This also has eliminated the joy some people took in filling the fountains with soap in the middle of the night and creating a bubbling mess to clean up the next day.)
  • An art installation called Horseshoe Falls Fountain on the corner of Marshall Way and Indian School Road creates fog as its water flows. During the first month of its installation this popular piece of public art used 50,000 gallons of water. The city curtailed the fog to two minutes at the top of peak hours and added a button that allows people to view the enticing fog for 30 seconds. These changes reduced the fountain’s water consumption to 1,500 gallons a month.20161109-scottsdale-water-feature-volcano-2

The technology that created both simple and spectacular fountains around the world freed people from the need to live close to natural rivers, lakes or streams. Fountains helped to create cities. Now cities are working to keep water as part of their art and architecture while making fountains as water-efficient as possible.

If you have a fountain or water feature in your yard, you can get help to make sure it’s operating efficiently by calling your city’s conservation professional.

For 47 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.

Salt and Verde: Protecting The Valley’s Water Supply

By Warren Tenney

The Salt and Verde rivers are two of the hardest working rivers in the United States.Traveling through Arizona’s northern high country and onto the desert plains, the Salt and Verde provide more than half of the AMWUA cities’ water supply. On November 15th, Phoenix Mayor Greg Stanton and Clarkdale Mayor Doug Van Gausig convened a meeting of mayors, councilmembers, city staffs and business leaders from Central and Northern Arizona to discuss how to keep the Salt and Verde healthy for the benefit of all their communities. This is another example of collaborative efforts to protect the rivers from the threats of fire and drought.


Thanks to the foresight of Valley landowners that formed the Salt River Project (SRP), the Salt and Verde rivers flow into SRP’s system of man-made lakes and reservoirs.  Water from the Salt and Verde is then distributed to homes and businesses in the Phoenix Metro area through canals operated by SRP.


Communities, businesses and environmental groups recognize that the forests, tributaries and groundwater that feed the Salt and Verde rivers are in the midst of a 20-year drought and water flowing in the two rivers has decreased by 35 percent. In the last 15 years, raging wildfires also have burned nearly 2 million acres of northern Arizona’s forests, where waters that keep the rivers flowing originate. These catastrophic wildfires cost the state hundreds of millions of dollars in fire suppression and economic development. Wildfires also leave behind a thick layer of sterile soil that washes into the Salt and Verde rivers and settles into reservoirs. The sediment makes the water delivered by SRP more difficult and expensive for cities to treat for drinking water.

Prescribed burn in Coconino National Forest

The first collaborative effort to address the stresses placed on the Salt and Verde rivers is the Northern Arizona Forest Fund.  Several AMWUA cities are contributing to the Forest Fund, which was spearheaded by SRP. The money is spent on forest thinning projects to protect the watershed.

Now the environmental group The Nature Conservancy has joined the effort to keep more water in the Salt and Verde rivers and ensure the quality and quantity of the Phoenix Metro area’s water supply. The Salt and Verde Rivers Water Fund aims to raise $7 million in the next three years to fund projects that protect these rivers for the communities in the Verde Valley and in the Phoenix Valley.  These projects include helping farmers along the rivers change to less water-intensive crops and to pay for automatic gates to make aging irrigation systems more efficient. The gates allow farmers to electronically control irrigation gates so just the right amount of water flows into irrigation channels to ensure crops thrive. Other projects under the Salt and Verde Rivers Water Fund could include thinning the forests to reduce the likelihood of catastrophic wildfires and protect the watershed.

Like any successful water management plan the new Water Fund relies on collaboration. At the meeting on November 15th, leaders from both the Valley and Northern Arizona discussed the state of the Salt and Verde, as well as how the Salt and Verde Rivers Water Fund could benefit users in both regions of the state. The meeting produced three key takeaways:

  • Your elected officials and cites are deeply engaged in water issues. This includes working with other leaders throughout the state to find innovate water solutions to our water challenges.
  • Initiatives such as the Water Fund show that unlike many of the battles of the past for precious water supplies, both urban and rural communities can find ways to come together to work on improving water security for all.
  • Although the Nature Conservancy has implemented pilot projects to demonstrate the range of possibilities for the Water Fund, the initiative is still in the planning stages. Ultimately, individual cities and communities must evaluate whether the goals of the Water Fund work for their citizens, businesses and communities.

The Salt and Verde Rivers Water Fund along with the Northern Arizona Forest Fund provide new avenues for cities in the Phoenix Valley and the Verde Valley to partner with environmental groups, businesses and farmers to protect and enhance Arizona’s water supplies at the source—high in Arizona’s forests and along its precious rivers.

For 47 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.

Arizona Is Big Winner Of Water Innovation Prize

By Warren Tenney

Pima County’s Southwest Water Campus is the winner of the New Arizona Prize: Water Innovation Challenge and it has a big job ahead of it. These creative water professionals intend to increase the public’s acceptance of reclaimed water – that’s highly treated wastewater – for drinking, in this particular case for drinking beer. While the winner received $250,000, the real winner is Arizona.


The projects presented by the Water Innovation Challenge winner and four finalists show Arizonans continue to find creative ways to make the most out of every drop of our water.  This innovative spirit comes from our heritage of finding ways to re-use, stretch, recycle and augment water resources in an arid land. 

The winning team from Pima County is going to create a traveling treatment plant – imagine a tractor-trailer – that will tour the State to show how today’s technology produces the highest standard drinking water from reclaimed wastewater. The project’s water pros will then challenge local brewers to craft the best beer in the State with that water. The goal is to help people become more comfortable with using reclaimed water for human consumption. Gaining public confidence in the technology through a beer tasting competition could win public acceptance for directly supplying this important resource for consumption.


This innovative proposal builds on Arizona’s previous pioneering efforts to put effluent to beneficial use.  Back in 1926, a treatment plant was built at the Grand Canyon Village for the purpose of reclaiming wastewater for non-drinking purposes.  In 1932, the City of Phoenix produced reclaimed water for agricultural uses.  Most notably, AMWUA negotiated in 1973 an agreement with Arizona Public Service (APS) to provide reclaimed water for cooling purposes at the Palo Verde Nuclear Power Plant, the only nuclear power plant in the world to be cooled with reclaimed water. Reclaimed water is also stored underground for later use.

One of AMWUA’s members, the City of Phoenix, was a top finalist with a proposal to create a market-based technological tool to help water managers throughout the state collaborate and develop opportunities to exchange water.  The expert-designed, data-driven tool would create the Arizona Water Exchange Program.  Options would be created in the context of current Arizona water law, drought dynamics, and Colorado River conditions.

Phoenix’s state-of-the-art proposal uses technology to build on Arizona’s history of collaboration.  From the Groundwater Management Act to creation of the Arizona Water Banking Authority, collaboration has been the key ingredient to solving water problems. Since 1969, AMWUA cities have worked together to supply safe, reliable water to their communities. 

Another finalist, Freshwater Systems Co., proposed using solar heat to treat Arizona’s abundant brackish or semi-salty groundwater to irrigate crops more efficiently and increase growth of winter crops. Treating brackish water builds on the idea of how desalination could benefit Arizona in the future. West Valley cities and others are looking at ways to treat salty water to help increase water supplies. 

Finalist WaterWorks@ASU has a plan to reclaim Arizona State University’s wastewater and use it in ASU’s cooling towers, among other applications.  The goal is to reduce the amount of drinking water used in cooling towers, which provide air conditioning in large buildings. ASU believes it would save 1.5 million gallons a day. This plan to treat and re-use wastewater on site is a big step toward making Valley buildings and campuses more water sustainable.

The last finalist, Friends of Verde River Greenway, proposed an exchange program that allows willing water users to temporarily reduce their water use and acquire “credits”. The credits can then be sold to water users who want to offset the impacts of their continued water use. The goal is to keep the Verde River flowing to benefit all those who use the Verde River including fish and wildlife, local residents and the Phoenix-area communities.  This new concept builds on the Valley cities’ long standing commitment to defend the Salt and Verde watersheds that generate water for the Phoenix area. It also builds on Salt River Project and The Nature Conservancy’s individual efforts to protect and manage our forests and watersheds.


The Water Innovation Challenge proves Arizona continues to create innovative solutions now to ensure ample water supplies for its future.

For 47 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.

Desert Landscaping: Ten Tips For Winter Watering

By Warren Tenney

Here’s one of the easiest ways you can save money and water: learn how to manage your irrigation controller. AMWUA cities’ conservation professionals continue to report that many homeowners, businesses and HOAs irrigate their landscapes throughout the winter as if it were still 110 degrees outside. It’s such a waste because most desert-adapted plants can make it through the winter months with little or no water. Even rye grass can thrive with a watering only every week or two.

Water efficiency professionals at AMWUA member cities offer ten important things to know about winter watering.

1.) A “sewer fee” is part of the water bill you receive each month from your city. Most cities recalculate this sewer fee each year based on a homeowner’s average water use during winter months. You can lower next year’s monthly sewer fee by cutting back on the amount of water you use this winter.


2.) Overwatering can kill your desert-adapted plants. The roots need the soil to dry out between waterings so they can absorb nutrients from the soil. Soggy soil prevents plants from pulling in essential elements, such as nitrogen and iron, and can suffocate the roots. This leads to yellowing leaves, poor health and even death.

3.) Some shrubs and vines will grow rapidly when overwatered in early winter months, exposing tender new tissue to colder temperatures. This can make them more susceptible to frost and damage the plants.


4.) Cactus plants suffer less frost damage if they have not been watered for several months before cold temperatures set in. Cactus plants hold water in their cells. When the water freezes it expands and ruptures the cells, which can damage or kill the plants.

5.) Overwatering during the winter is more likely to produce pools of water in your lawn and around your plants that won’t evaporate as quickly as they would in summer. These puddles mixed with mild winter temperatures can breed mosquitoes. If you seem to have more of the pests around your patio and yard, check your irrigation schedule – you may want to let your yard dry out. During the winter, water also can pool near a home or building’s foundation, which can damage the foundation and invite pests, including termites.

6.) Most of your cities have water efficiency professionals with the right tools who can help business owners, apartment or facilities managers, and HOA board members determine precisely how much water a particular landscape needs to thrive. If you want to lower your water bill, give your city’s water efficiency professional a call and ask for help.


7.) It’s the time of year when your winter rye grass is established. That means your grass no longer needs the same amount of water as it did when you were germinating rye grass from seed. The sprinklers only need to come on once every seven to 10 days. You can cut back watering to once every two weeks in December and January. Established rye grass needs to be watered to a depth of 4 to 6 inches. Use a small wood stake or a screwdriver to check how deep the water has sunk into the yard.

8.) It’s not wise to assume your landscaper understands how to water desert-adapted plants and trees throughout the year without your direction. Let your landscaper know saving water is just as important as having the yard visually appealing.  You can also take matters into your hands and learn how to manage your own irrigation controller. Most controller manufacturers have how-to videos on YouTube as well as toll free help lines. Check with your city. Some offer free classes or videos about how to operate your irrigation controller.

 9.) It’s possible you are overwatering parts of your yard and don’t know it. While the weather is cool, occasionally turn on your irrigation system to find and fix leaks you may not see if you are irrigating during the night. When temperatures remain above freezing, night is the best time to water because less water evaporates.


10.) Trees should be watered deeply but far less often in winter. Native Palo Verde, mesquite and acacias only need a good soaking once a month. Other trees should only be watered once every two to four weeks.

If you need more details about watering a desert landscape you’ll find them at Water – Use It Wisely Landscape Watering Guide. It’s worth the effort because homeowners use up to 50 percent to 70 percent of their water outside. That’s why your city’s water department offers free classes, free videos, free brochures and free professional consultations to help you save water and enjoy a thriving landscape all year. Find out more at amwua.org/landscape.  Winter is the best time of year in the Phoenix Metro area and the best time of year to save water.

For 47 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.

On The Job: Chemist Ensures Safe Water Flows To Your Home And Business

By Warren Tenney

Mark Xerxis is a chemist, but don’t imagine him behind a set of tubes, Bunsen burners and microscopes. Mark runs the metals lab within Scottsdale’s Water Quality Laboratory, which means assuring Scottsdale’s water never has a problem with elements such as arsenic, chromium, lead or copper. His main tool is something called an Inductively Coupled Plasma Mass Spectrometer. Mark gets up from his chair and writes the name on a white board. The piece of equipment looks like a giant copying machine with silver tubes venting out of the ceiling. Each morning it is Mark’s job to maintain, calibrate and optimize all the machines in his lab before running the daily samples, up to 60 a day.


Mark Xerxis runs the metals lab within Scottsdale’s Water Quality Laboratory.

Scottsdale and all the AMWUA cities take numerous daily samples from their drinking water systems, wells, or wastewater treatment plants. Mark tests Scottsdale’s samples for about 30 metals. The U.S. Environmental Protection Agency (EPA) regulates most of the metals that can be found in water. The lab also monitors for metals that could be regulated in the future, known as “emerging contaminants.” EPA will change the amount of metal permitted in water if it has new data to support a revised regulation. For example, in 2006 the EPA changed the level of arsenic permitted in American drinking water from 50 parts per billion to 10 parts per billion. That required new equipment in the treatment plants and new testing in the labs.

Preparing himself for all this responsibility didn’t come easy for Mark. He arrived in the United States – Arizona specifically – in 1987 at age 19 speaking only Polish. His mother and father were active in Poland’s anti-communism Solidarity Movement when the movement’s protests – as well as its members – were violently suppressed. First his mother, then his father, made their way to the United States as political refugees. Mark and his sister joined their parents several years later.

Mark entered North High School in the Phoenix Union High School District as a senior. He credits the school’s English as a Second Language program for teaching him English quickly and well enough to move on to Phoenix College. There he pursued chemistry, a science that had enthralled him since he was a young boy. He kept studying and earned a Bachelor’s of Science degree in Chemistry from Arizona State University.

“You see people come here (the United States) and surround themselves with people who don’t speak the language and they don’t need to learn it,” Mark said, who understands how hard it is to learn a new language but calls not learning English a mistake. “Eventually, it backfires.”

After several years working as a chemist in private industry, Mark applied and was hired to work in Scottsdale’s Water Quality Laboratory. That was 17 years ago. Mark’s colleagues are responsible for four other labs within Scottsdale’s main lab where they monitor for organic and inorganic compounds as well as microbial contaminants. Mark and his fellow scientists are cross-trained to step into each other’s labs and take charge when necessary.

Water treatment is always moving forward and new processes are regularly being tested. Mark’s favorite days are when he gets to evaluate something new, like a proposed water treatment system. It’s up to the lab’s scientists to provide data about the strengths and weaknesses of a new treatment option, which often requires more than scientific know-how. Mark’s job includes presenting his findings to the city’s technical group as part of the decision making process. Also, Mark often makes presentations to explain the results of his experiments at industry conferences to help other cities optimize their treatment and testing processes.


Mark mountain bikes year round, but his adventures don’t always go as planned.

Mark, 47, lives with his wife and four rescued dogs in Apache Junction. Once out of the lab, it’s likely you’ll find him in the mountains. Truth be told, he’s a bit wild in his off hours. Here’s an example: On the hottest day of each Arizona summer the scientist straps to his back a hydration pack filled with ice and water (tap water never bottled: “I think it’s a waste of money. I work in the field, I test water and I know it is completely safe to drink.”). Then he puts a charged cellphone in his pocket and at 3 p.m. goes for a 10-mile mountain bike ride in the desert – just because he can. This year it was 117 degrees when Mark did his annual ride in the Usery Mountains. While he claims to be impervious to the heat, Mark doesn’t hesitate to show you photos of the time he was test-driving a new bike and suddenly veered into a patch of notoriously painful Jumping Cholla cactus.

In the summers, Mark works with high school students who intern at the laboratory. He likes to watch their eyes widen when they see the city’s array of equipment. Part of his job is to help them design an experiment and make a presentation to staff. One student decided to measure the metals in a cigarette so she could explain to her father the exact amount of metal he had taken into his body during his 20-year smoking habit. Mark said he has faith in the next generations of scientists to continue keeping cities’ water safe.

“It’s the best job there can be,” Mark said, calling himself just one member of a team that gets things done right. “It’s the people, the management, the science. Scottsdale has the best mix of everything. It’s very satisfying.”

For 47 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit amwua.org.

Putting Storm Runoff To Work

By Warren Tenney

Cities in the Phoenix Metropolitan area are experimenting with building methods to slow storm runoff and allow more of it to be absorbed into the ground instead of rushing into streets and down storm drains. Low Impact Development (LID) is an approach to land development – or redevelopment – that mimics the natural environment by encouraging rainwater to stay in place and to sink into landscaping and planters, soak through sidewalks and parking lots made of permeable pavement, pour off roofs into cisterns and rain barrels, even collect on rooftop gardens. LID practices aim to preserve, restore and create green spaces using soils, vegetation, and rainwater harvesting. The City of Tempe has just taken a big step forward in determining how to make LID work for desert cities.

Cities are taking a hard look at Low Impact Development methods for building streets, commercial developments and planned residential communities. The methods could reduce water used to irrigate landscaping, prevent street flooding, and allow cities to downsize expensive storm drain systems. For example, the City of Phoenix maintains an 895-mile underground storm drain system. During the Valley’s infrequent but often hard and fast rainstorms, runoff rushes into 18,641 catch basins cut out of Phoenix sidewalks and along streets or into grated dry wells often located in parking lots. Many of the storm drains eventually empty into the Salt Riverbed.

Last year, the cities of Mesa and Glendale, working with the consulting firm Logan Simpson, created the Low impact Development Toolkit, which offers technical variations of techniques that make the most out of storm runoff. Mesa and Glendale have used Low Impact Development techniques on several public projects and plan more. For example, Mesa used curb cuts that allow runoff to collect in shallow basins and irrigate street landscaping around Fiesta Mall, along Southern Avenue at Alma School Road. Glendale used permeable pavement in a 6-acre park-and-ride lot at 99th and Glendale avenues where water sinks through the pavement and into the ground.  

Now, Tempe is adding another piece of critical information about Low Impact Development in desert cities. Tempe, working with the Flood Control District of Maricopa County and contractor J2 Engineering & Environmental Design, used new technology to create a model that divided most of the city into 20-square-feet grids. New highly detailed topographical maps allow engineers to know how much grass, pavement and gravel are contained in each grid and if there are buildings or fences or walls. Then consulting engineers used computer-modeling techniques to determine what happened to runoff in each grid during the lightest to the heaviest rainstorms. Linking the grids has given the city the most accurate storm runoff data available. (These computer-modeling methods have been around for many years, but only within the last 5 years have typical computers been powerful enough to model entire cities.)


Tempe neighborhood as it is now.


Model of Tempe neighborhood with LID techniques.

Here’s the interesting part: Tempe and its consultant modeled a small portion of a neighborhood with a history of flooding problems by dividing it into even smaller 4-square-feet grids. The city then overlaid the model with different Low Impact Development techniques. This model produced the state’s most detailed and quantifiable data about the effect of Low Impact Development techniques on storm runoff. The small section of the neighborhood was modeled using different Low Impact Development methods, such as driveways made of permeable pavement and yards contoured to hold water and release excess water into permeable underground pipes. The model included street landscaping created with curb cuts and swales to hold stormwater and even a roof garden on a nearby school building. Runoff was measured using different combinations of Low Impact Development techniques and different percentages of homeowners using the techniques.

Here’s what the City of Tempe found out: If 50-75 percent of homeowners agreed to participate and applied the suggested Low Impact Development techniques to their property, flooding would be mitigated enough to downsize a proposed new storm drain system for the area. The city has concluded that retrofitting established neighborhoods with Low Impact Development techniques is possible and worthwhile. 

Making it work, however, would require a partnership between homeowners and the city and that needs more research. What is the best approach to engage and assist residents to apply Low Impact Development techniques to their yards?  What tools and information will they need?  Would rebates be an effective means to encourage homeowners to invest in revamping their landscapes and driveways, similar to turf removal incentives? 

For now, these Low Impact Development techniques would be most practical when used on public property, such as parks, streets and sidewalks, and when they are built into large new residential or commercial developments or redevelopments.

Quantifying the effect of Low Impact Development is a big step toward helping it to gain traction in desert cities.  Cities will be able to demonstrate the value of integrating these techniques into the community to better manage stormwater, reduce infrastructure costs, potentially offset landscape irrigation, and to enhance our built environment.

For 47 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.