Bringing water from the Conservation Effluent Pool into action.
Good news broke last March at Santa Cruz River Research Days: Pima County received approval to permanently allocate water to sustain river flows benefiting plants and aquatic wildlife. With this decision, we are one step closer toward our goal to make sure that water flows in the rivers of the West for generations to come.
During the heat of June and July, portions of the Santa Cruz between the Agua Nueva wastewater treatment facility and Tres Rios facility have intermittently run dry. This new water allocation will help prevent dry spots in the river where endangered Gila topminnow and native plants have rebounded in recent years.
County supervisors approved the proposal bringing water from the Conservation Effluent Pool (CEP) into action.
County supervisors approved the proposal bringing water from the Conservation Effluent Pool (CEP) into action. The CEP was created through an intergovernmental agreement with Pima County and the City of Tucson 20 years ago but remained unused until now. The award to Pima County Regional Flood Control District marks the first successful proposal under the CEP.
The Pima County proposal was different from previous application attempts because it used the presence of an endangered species and compelling, long-term data. This proved to be the justification needed to award the CEP request. The proposal included Living River project data to demonstrate when and where the Santa Cruz ran dry and showed that Gila topminnow occurred in the same area. Annual fish survey records noted the presence of the fish beginning in 2017 and then in 2019 and 2020, the Gila topminnow were observed in the intermittently dry stretch that the CEP allocation aims to prevent. And Living River data were essential to calculate how much water would be needed to reduce (and ideally eliminate) this habitat from drying out.
Living River data were essential to calculate how much water would be needed to reduce (and ideally eliminate) this habitat from drying out.
This first-ever CEP allocation maintains a minimum of 5 million gallons of effluent, or highly treated wastewater, to be released per day to sustain ecosystem conditions. The successful approval sets a precedent for riparian protection in Pima County and serves as a model for other parts of the river. The decision also reinforces why we conduct research, develop partnerships, and report on conditions, improvements, actions, and management of the Santa Cruz River. Our newest Living River report highlights the success of this first CEP allocation with several other notable achievements along the Santa Cruz River from downtown Tucson to Marana.
Note: Tucson Water and the City of Tucson later successfully applied for CEP water for the Heritage Reach of the Santa Cruz in downtown Tucson.
Blog post by Luke Cole, associate director