Phoenix Waste Water Reclamation
"Tres Rios Hayfield Site"
(Presently Closed to the Public)

Introduction

For most people the idea of a weekend visit to the city wastewater treatment facility does not suggest a pleasant and relaxing outdoor experience. Yet a visit to the City of Phoenix Wasterwater Reclamation site, a.k.a Tres Rios, is a surprising and wholesome adventure! Wildlife and flora are abundant here ... after all this is a desert where an abundance of water of any kind makes for an oasis. Modern sewage treatment is a far cry from what it was decades ago. Today the water emerging from this state-of-the-art sewage treatment system is nearly odor-free, and, first and foremost, it is safe for wildlife and visitors. Certainly the Salt River environment of 150 years ago would have had much more aesthetic appeal, but given that time travel can only be arranged through imagination we should recognize this as a valuable wildlife resource. Amazingly there are beavers, bobcats and raccoons among the wildlife here in Phoenix! The name Tres Rios refers to the confluence of three nearby rivers: Gila, Salt and Agua Fria.

Birding and nature watching are the primary attractions and with the rapid growth of large willows, mesquites and cottonwoods there are plenty of shaded paths and secluded glades. To reach the facility from I-10 in west Phoenix/Tolleson - Exit # 134, then drive south on 91^st Ave. about 6 miles.

Flame Skimmer

"Balance of Nature"

This is a great spot to learn about nature, particularly man's impact and place in the natural environment. There are many signs and kiosks describing the finer points of the wildlife, plant life and the roll of water in the desert. Some of these signs refer to a ‘Balance of Nature’. It is not clear what this means given that Tres Rios has an unnatural abundance of water, nitrogen and phosphorous fertilizers, and plenty of construction disturbances.

There is standing water in the marshes and ponds that serve as a final treatment system for the wastewater before it flows on down the Gila River. Through careful manipulation of the water flows and levels, addition of gambusia fish, conservation of dragonflies, swallows and bats the populations of mosquitoes can be managed to low levels, but not eliminated. Visitors should wear light, loose clothing that covers most skin area and also apply mosquito repellant. Non-biting midges (chironomids) are common here, look very much like mosquitoes, but are completely harmless to people.

I have been informed by Ron Elkins, the Process Control Specialist at Tres Rios Wetlands, that only natural, biological control bacteria are used at Tres Rios and only as larvicides in the water to target the immature larval stages of mosquitoes. No chemical pesticide sprays are used on the project nor within 400m. This careful management is likely not employed on all nearby properties where additional methods including adulticide chemicals are used. The result is a disruption in the relationships between some plant feeding insects and their natural enemies; these effects are not localized and may spread about for dozens of kilometers. The cottonwood trees, for example, are struggling to survive under heavy loads of leaf miners (click thumb-image at right for details), there are many aphids on many kinds of plants, and leaf beetles are abundant on the water primrose. Dolichoderine ants are making out fine; their habits allow them to reap the abundance of honeydew produced by the aphids.

Does this mean that Tres Rios is not a safe environment for families and citizens? No, it is likely safer than even your own yard! Mosquito control is a vital component of all human communities because mosquitoes are vectors for things like West Nile Virus and Equine Encephalitis. Chances are that your neighborhood has unmaintained swimming pools and bird-baths with breeding mosquitoes left unchecked. Others in your neighborhood likely run out to the home improvement store for pesticides upon spotting anything crawling or flying about. And, chances are they did not read or follow the directions on the container sufficiently to protect the local environment. The operators in cooperation with local and state vector control specialists at Tres Rios, on the other hand, follow the regulations and best insect pest management (IPM) practices to maximize the safety and health of the environment and for visitors.

Birds

The complete list is way over 100 - these are just the more common ones:

1. Mourning Dove -- S,F,W,Sp
2. European Starling -- S,F,W,Sp
3. American Coot -- Fulica americana -- F,W,Sp
4. Snowy Egret -- S,F,W,Sp
5. Great Egret -- Ardea alba -- S,F,W,Sp
6. Great Blue Heron -- S,F,W,Sp
7. Green Heron -- S,F,W,Sp
8. Abert's Towhee -- Pipilo aberti -- S,F,W,Sp
9. Common Moorhen -- Gallinula chloropus -- S,F,W,Sp
10. Yellow-rumped Warbler -- Dendroica coronata -- F,W,Sp
11. Orange-crowned Warbler -- F,W,Sp
12. Northern Mockingbird -- S,F,W,Sp
13. Killdeer -- S,F,W,Sp
14. White-faced Ibis -- S,F,W,Sp
15. Cliff Swalllow -- Sp,S
16. Black-crowned Night-Heron -- Nycticorax nycticorax -- S,F,W,Sp
17. Verdin -- S,F,W,Sp
18. House Finch -- S,F,W,Sp
19. Mallard -- S,F,W,Sp
20. Pied-billed Grebe -- F,W,Sp
21. Neotropic Cormorant -- Phalacrocorax brasilianus -- S,F,W,Sp
22. Double-crested Cormorant -- Phalacrocorax auritus -- S,F,W,Sp
23. Greater Yellowlegs -- F,W,Sp
24. Great-tailed Grackle -- S,F,W,Sp
25. Anna's Hummingbird -- S,F,W,Sp
26. Loggerhead Shrike -- Lanius ludovicianus -- F,W,Sp
27. Black-tailed Gnatcatcher -- Polioptila melanura -- S,F,W,Sp
28. Black-throated Sparrow -- S,F,W,Sp
29. Gambel's Quail -- S,F,W,Sp --
30. Brown-headed Cowbird -- S,F,W,Sp
31. Greater Roadrunner -- S,F,W,Sp 
32. Lesser Nighthawk -- S

34. Cactus Wren -- S,F,W,Sp
35. Curve-billed Thrasher -- S,F,W,Sp --
36. Phainopepla -- W,F --
37. Belted Kingfisher -- Megaceryle alcyon -- F, W
38. Black Phoebe -- S,F,W,Sp
39. Brewer's Sparrow -- Spizella breweri -- W,F,Sp --
40. Common Raven -- Corvus corax -- W
41. Black-throated Gray Warbler -- Sp,F

Mammals

1. Desert Cottontail
2. Rock Squirrel
3. Beaver -- the visitor will find chewed tree trunks as evidence of their nocturnal industries
4. Bobcat

Shrubs and Trees

1. Salt Cedar (Tamarisk pentandra)
2. Quail Bush (Atriplex lentiformis)
3. Four-wing Saltbush (Atriplex canescens)
4. Velvet Mesquite -- Prosopis velutina
5. Screwbean Mesquite (Prosopis pubescens)
6. Tree Tobacco (Nicotiana glauca)
7. Desert Seepweed -- Suaeda moquinii
8. Fremont Thorn Bush -- Lycium fremontii -
9. Seep Baccharis (Baccharis salicifolia)
10. Fremont Cottonwood (Populus fremontii)
11. Graythorn ( Zizyphus obtusifolia)
12. Desert Senna (Senna covesii) -- planted along roadside
13. Blue Palo Verde (Parkinsonia florida)
14. Mexican Palo Verde (Parkinsonia aculeata)
15. Giant Reed -- Arundo donax - a grass really, looks like bamboo and stands 5 to 10 m tall.
16. Desert Broom (Baccharis sarothroides)
17. Alkali Goldbush (Isocoma acradenia)

WILDFLOWERS

Blooming Summer & Fall

Quailbush

Silver-leaf Nighshade

Screwbean Mesquite

Devil's Claw

Graythorn

Sacred Datura

Desert Tobacco

Wire Lettuce

Desert Marigold

Jerusulem Thorn

Salt Marsh Fleabane

Alkali Goldenbush

Annual Sunflower

Quailbush

Floating Water Primrose