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Making Big Waves: Spring 2021 ALRS Graduate Featured in a Documentary & Has Thesis Published

Dr. Drew Eppehimer, an ALRS graduate of Spring 2021, and his advisor, Dr. Michael Bogan, were recently featured in a mini dciumentary produced by PBS Arizona Illustrated, "An Unnatural River." To watch the documentary, please click here:

Two wastewater treatment facilities in Tucson feed treated effluent to the Santa Cruz River fostering abundant native vegetation and wildlife along with new recreational and economic opportunities. One hundred percent of the water flow in the lower Santa Cruz comes from recycled water during non-rainy times. Researchers at the University of Arizona sought to discover how varied water use in the city impacted water flows and how those flows impacted the diversity of aquatic insects in the river. What they discovered revealed a great deal about the health of the river and the growing number of species who call it home. To find out more about research projects being conducted at the University of Arizona’s School of Natural Resources and the Environment, visit

In addition, an articled from his dissertation was just published in River Research and Applications:

Title: Daily flow intermittence in an effluent-dependent river: Impacts of flow duration and recession rate on fish stranding

Lay Abstract:

Treated wastewater is often discharged into streambeds where it can augment or create aquatic habitat in arid regions. However, where no natural baseflow is present, discharge fluctuations result in daily stream drying and rewetting. In this study, we documented flow intermittence and resulting fish stranding on an effluent-dependent reach of the lower Santa Cruz River in Tucson, Arizona. We observed an average of 27 fish strandings per day. Ninety-nine percent of observed fish were Poeciliidae: all were likely the non-native western mosquitofish (Gambusia affinis). Duration of flow prior to drying (increased recolonization potential) and flow recession rates (increased stranding likelihood) were positive predictors of fish stranding. As urban development continues, the discharge of effluent into rivers and streams will become more common throughout the world. Continued research is needed to understand the benefits and challenges presented by these effluent-driven flow regimes, including their impacts on aquatic taxa.

Last updated 3 Sep 2021