PIMA COUNTY, Arizona — Improved water quality in the Lower Santa Cruz River resulting from upgrades to Pima County’s wastewater treatment facilities have allowed the return of a native species of fish to the Tucson area for the first time in more than 70 years.

Fish surveys conducted in November confirmed the presence of the Gila topminnow, an endangered species. Previous annual fish counts of the Santa Cruz had detected only non-native fish species in the Tucson section of the river.

The fish surveys were conducted by Pima County and partner organizations including the Sonoran Institute, U.S. Fish and Wildlife Service, Arizona Game and Fish Department, University of Arizona, and U. S. Geological Survey Arizona Cooperative Fish and Wildlife Research Unit. The surveys took place at four sites along the river, from near Silverbell Park in the south to Marana Heritage River Park in the north. The main focus of the surveys was to determine the species living in the river and their relative abundance.

“It is extremely gratifying to see the topminnow return to a stretch of the river where they haven’t been seen for decades” said Brian Powell of Pima County’s Office of Sustainability and Conservation. “They used to be one of the most-common native fish in Southern and Central Arizona. However, after the turn of the 20th Century, population growth, groundwater pumping and competition from non-native fish like the mosquitofish pushed them to near extinction. For many years, the only significant population in this part of the Gila River Watershed existed in Upper Sonoita Creek and parts of northern Sonora, Mexico.”

While this is the first time a native fish has been found in this stretch of the river, the number and variety of species has been increasing in recent years. This is due almost entirely to upgrades to Pima County’s two metropolitan wastewater treatment facilities that now produce exceptionally clean effluent. These facilities then discharge this treated effluent to the Santa Cruz River. The County began operations of the expanded and upgraded Tres Rios Water Reclamation Facility (WRF) at Ina Road and the new state-of-the-art Agua Nueva WRF near Camino del Cerro Road in 2013.

In addition to the improved the aquatic habitat as a result of higher-quality water leaving the facilities, the improvements have increased the amount of water naturally recharging the local aquifer. Gone too are the terrible odors that once emanated from the treatment of wastewater. These improvements, along with investments in infrastructure and recreation opportunities such as The Loop multi-use path, have made it easier and more enjoyable for residents to discover the flowing Santa Cruz River.

Evan Canfield, the Regional Flood Control District’s Project Manager on the Living River Project, which tracks conditions in the Santa Cruz, considers the Gila topminnow’s return a validation of Pima County’s efforts to restore the river to a more natural, functional state.

“In a very real way, the return of the topminnow is emblematic of the improving river conditions,” Canfield said. “In our first fish survey for the Living River Project four years ago, we found almost no fish in this part of the Santa Cruz. Today the river supports a population of endangered fish. This shows we’re moving in the right direction.”

The RFCD has begun an updated management plan for the Santa Cruz to recognize that the river is an increasingly valued community resource and attraction that also needs to be managed to safeguard property and ensure public safety.

The presence of an endangered species in the Santa Cruz River will not impact County operations along the river because of the County’s Section 10 permit issued by the U.S. Fish and Wildlife Service. The County anticipated and planned for the possible establishment of topminnow and other federally protected species to the river, as well as impacts to them from activities covered in the permit.

Newly released Living River Report demonstrates sustained improvements

TUCSON, ARIZONA — Pima County and the Sonoran Institute have completed the final EPA-funded report in a series entitled A Living River. The new report describes the conditions of the Lower Santa Cruz River between October 1, 2015 – September 30, 2016 and how things have improved since Pima County expanded and upgraded Tres Rios Wastewater Reclamation Facility and constructed the new state-of-the-art Agua Nueva Wastewater Reclamation Facility in 2013. The resulting improved water quality now supports more diverse aquatic wildlife, is sustaining an increase in river recharge (double the volume before upgrades), and is enhancing a valuable community amenity.

The Lower Santa Cruz River flows year-round through northwest Tucson and Marana, with most of the water coming from two regional water reclamation facilities. This stretch of the Santa Cruz River provides the longest length of river dominated by effluent in the state.

“Conditions along the river have changed dramatically since the upgrades to the Wastewater Reclamation Facilities in 2013,” Sonoran Institute Ecologist Claire Zugmeyer said. “The fact that we’ve found five species of fish in the river since 2015 speaks volumes to the improvements in water quality.”

Prior to the upgrades, only one species of fish was found, and though current species are all non-native, their presence demonstrates one of the many benefits of releasing high quality water into the river.

Additional highlights from this year’s report include: further improvement in water quality and clarity, wetland plant cover varied with water presence in the river’s drying sections and continued minimal levels of odor escaping the reclamation facilities.

The Pima County Regional Flood Control District and the Sonoran Institute are hosting an event to celebrate the river and the release of the latest report from 4–5 p.m. on Thursday, Sept. 14 at the Joel D. Valdez Main Library, 101 N. Stone Ave. The Sonoran Institute will host an informal social hour at 5:30 p.m., at Borderlands Brewing Company, 119 E. Toole Ave., following report presentations from expert speakers.

In addition to continued monitoring of river conditions with the Living River Project, Pima County Regional Flood Control District is building on this effort by developing a management plan for the Santa Cruz starting with the stretch from Grant to Trico Road. Year-round flows often result in wear and tear to the bank protection, requiring frequent repairs and an ongoing need to manage changing river conditions to prevent flood damage and ensure the Santa Cruz 3 continues to serve as an amenity to the community.

“Our goal is to determine what Pima County residents value about the Santa Cruz River so that we can continue to achieve community benefits as well as provide flood safety,” Evan Canfield, Civil Engineering Manager, Pima County Regional Flood Control District, said.

To that end, the Sonoran Institute, has developed a survey intended to gauge public priorities, values, and concerns for the river. Participation in the online questionnaire is anonymous and the feedback will help with the formation of long- and short-term management strategies for the Santa Cruz River. The deadline for submitting answers is September 15, 2017.

This online survey is a companion to upcoming community workshops where the Sonoran Institute and Pima County will gather feedback on the public’s values and concerns, building a vision for the river. These workshops will be at the following locations and times:

• Ellie Towne Flowing Wells Community Center
  • October 10, 6–7:30 p.m. (Focus area – Grant to Ina Road)
• Town of Marana Municipal Complex, 2^nd Floor Conference Room
  • October 12, 6–7:30 p.m. (Focus area – Avra Valley to Trico Road)
• Wheeler Taft Abbett Sr. Library
  • October 18, 6–7:30 p.m. (Focus area – Ina to Avra Valley Road)

According to Zugmeyer, “The Living River project is helping to connect people to the river. We’re thrilled to be taking this work to the next level by facilitating a dialogue and collecting community ideas that will shape the future of the Santa Cruz. This effort is critical for reconnecting Tucson to the river that has nourished and sustained our community for thousands of years.”