Assessing Water Quality and Potential Nutrient Sequestration in A Rejuvenated Reach of the Urban Salt River

The Salt River in Arizona has been dammed and rerouted away from its natural channel for human use since the late 1930s. Once a thriving hydrological ecosystem and riparian zone, the scar of a dry riverbed snakes through Phoenix, Arizona. The exception to this dry riverbed is a 10-kilometer, lush, riparian corridor to the west of Phoenix where ecosystem rehabilitation has been enabled by the effluent of the Tres Rios Constructed Treatment Wetlands (CTW). This study investigated the ecosystem health of this stretch of river, referred to here as Rio Verdadero, by identifying how water quality is impacted as it flows from east to west. To quantify key water quality indicators, water samples were collected every two months during 2024 at three locations along the river: The Tres Rios CTW outflow, The Base & Meridian Wildlife Area, and the Lower Buckeye Diversion Dam. Additionally, CTW outflow data were used to estimate rates of nutrient sequestration by the riparian ecosystem. Results showed a decline in nutrients and improvement of water quality downstream of the Tres Rios Wetlands, indicating a healthy, functioning riparian ecosystem as a result of natural rehabilitation and intentional restoration that has taken place in the last 15 years.