Planning your Trip

Tres Rios, meaning Three Rivers, is an impressive project near the confluence of the Salt, Gila, and Agua Fria Rivers west of Phoenix. Owned and operated by the City of Phoenix Water Services Department, this series of wetlands provides flood protection for the local residents, restores vital habitat for native plants and animals, and improves water quality. Highly treated effluent from the adjacent 91st Avenue Wastewater Treatment Plant provides the water needed to sustain this complex project.  

What is Tres Rios? 

Tres Rios consists of a flood protection levee, effluent pump station, emergent wetlands, riparian corridors, and open water marsh areas to replace existing non-native salt cedar in the river. Construction of the levees and emergent wetlands has been completed, with construction of the pump station and riparian and river areas currently underway. 

Where Does the Water Come from? 

The water source for Tres Rios is the highly treated effluent from the 91st Avenue WWTP. In order to get this water to the wetlands, a 300 million gallon per day pump station was constructed within the Wastewater Treatment Plant. Along with providing water to sustain the wetlands, the pump station ensures the Treatment Plant can operate when water is flowing in the river.

Flow Regulating Wetlands – Closed to the Public 

The 290 acres of wetlands inside the fence serve an important function:  further cleaning the highly-treated effluent from the 91st Avenue Wastewater Treatment Plant before it is discharged to the Salt River. Nutrients and toxic compounds are physically removed or transformed by bacteria residing on the bottom of the ponds and on plant surfaces. Aquatic plants produce oxygen, which helps kill bacteria and pathogens. Not only do wetlands help treat the water, but they also provide a suitable habitat for waterfowl, mammals, amphibians, and insects. The three separate cells also equalize daily variations of flow to control the volume of water discharge to the Salt River.  

Overbank Wetlands 

The Overbank Wetlands consist of 128 acres of constructed emergent wetlands along the North Bank of the Salt River. Riparian “stringers” of cottonwood and willows provide a connection to each of the cells and vital habitat for many species of birds. 

Mesquite Bosque

Running parallel of the Overbank Wetlands is a large linear mesquite forest.  Hidden among the hundreds of mesquite trees and the occasional palo verde, you may see a roadrunner, coyote, cottontail rabbit, or maybe even a bobcat!