Tres Rios Wetlands

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We’ll take you to the Tres Rios Wetlands in West Phoenix, which uses effluent water from a wastewater treatment plant to create an unexpected wetlands area in the desert.

Ted Simons: Tonight's look at Arizona sustainnability focuses on Tres Rios, 480 acres of man-made wetlands near 91st avenue and baseline. We go to this resource north of the Salt River.

Ron Elkins: Adolescent states were rocky. We were manhandling this place. We got it under control and part of it was trying to get the environment to stabilize itself to where it knew what it was, giving itself an identity.

Dan Childers: Desert productivity is limited by water availability. In aquatic systems water is not an issue so more often than not the productivity of the system is limited by one of two what we call macro nutrients. The same things that you find in fertilizer. Nitrogen and phosphorus. In Arizona the limiting nutrient is nitrogen. If you get too much of the nutrient controlling the eco-system the system becomes too productive, you get fish kills and it's no longer safe to drink. The water that leaves our houses and in pipes when we take showers, flush toilets, wind up at a very sophisticated waste water treatment plant. There are maximum amounts of nitrogen the city is not allowed to discharge into the Salt River. The city could have very easily made the waste water treatment plant across the street technologically able to get all of the nitrogen out of the water. It would have been very expensive and energy intensive.

Ron Elkins: Just in facilities it would probably be well over $5 billion.

Dan Childers: Instead they chose an easier route. We'll spend a fair amount of money up front designing and building the thing and then we basically we sit back and let nature do the work for us.

Larry Westerman: Tres Rios was more like a polishing filter. It takes our effluent, which has really good nitrogen removal, and it knocks it down even farther.

Dan Childers: We were as eco-system ecologists are interested in how the system is working, how it's doing the job the city is expecting it to do, so we thought if you put a wetland in a very hot, dry climate it's going to be losing a whole lot of water to the atmosphere.

Chris Sanchez: That is what we were worried about, this increasing draw-down of water will concentrate whatever is in the water, stress out the plants, make it harder for them to do their job and obviously decrease the performance of the system.

Dan Childers: For the first time ever we documented what we call the biological tide, effectively a very gradual movement of water into the Marsh that's completely driven by the biology of the plants. We have lots of evidence that if nitrogen gets into the Marsh it gets completely expunged from the water. This biological tide phenomenon is doing a better job than if it was in a cooler place or more moist place. When you have a natural eco-system or one like this that does something that benefits humans it's providing an eco-system service. That job of nitrogen removal was the eco-system service of design, but what we saw happen out here was another eco-system receives that -- service the city was not expecting, that was this place became an absolute mecca for wildlife, especially for birds.

Tice Supplee: For people in the Audubon and biologists, we weren't surprised at all. We firmly believed in this situation if you build it these birds will come and they will use these resources. The Tres Rios is really key for water birds and waterfowl that come to spend the winter.

Dan Childers: There's a flock of three or four dozen white pelicans that wintered here three winters ago and never left. It's home to dozens and dozens of different species of wetland and aquatic birds and that's really cool. Most of the water that's going from this system here being discharged into the salt flows downstream and hits what's called the lower Buckeye diversion dam.

Ron Elkins: And then that water is utilized for agriculture uses.

Tice Supplee: As we go into the future and recycling and reusing water we'll always have this as being a component of it.

Dan Childers: I have spent my entire career studying wetlands from the very holistic perspective so there's something very cool about working in a system that was specifically designed to do a job thanks to the birds and other wildlife it's doing other jobs that we weren't expecting. I love wetlands. It doesn't matter where they are, what they are doing, what they look like. They are amazing places.

Ted Simons: Tres Rios provides eco-tourism for the region, flood protection for local residents and as you saw, habitat restoration for plants and wildlife. For more information on Tres Rios, you can find it at the city's website,

Ted Simons: Thursday on "Arizona Horizon" hear from Clint Hickman, new chair of the Maricopa County board of supervisors and we'll speak with a creative designer on how pop culture impacts technology. That's at 5:30 and 10:00 on the next "Arizona Horizon." That is it for now. I'm Ted Simons. Thank you so much for joining us. You have a great evening.

Video: "Arizona Horizon" is made possible by contributions from the friends of Arizona PBS. Members of your PBS station. Thank you.

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