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Press Release
Water Quality

PHOENIX (Mar. 22, 2023) — Arizona Department of Environmental Quality (ADEQ) today announced the provisional delisting of Fossil Creek and a segment of the San Pedro River near Winkelman from the state’s Clean Water Act (CWA) 303(d) Impaired Waters List, bringing the calendar year 2022 provisional waterbody delistings to a total of eight. The Impaired Waters List identifies Arizona waters that do not meet applicable state water quality standards. Fossil Creek and a segment of the San Pedro were both previously listed as impaired in the Arizona 2022 Clean Water Act Assessment for exceeding the Escherichia coli (E. coli) surface water quality standard. These impairments will be officially removed from the list pending final approval by the U.S. Environmental Protection Agency (EPA).

Samples for these waters were collected by volunteers through Arizona Water Watch, ADEQ’s Community Science Program. Volunteers collected approximately 6,900 samples in the 2022 calendar year. The estimated value of this sample collection effort is more than $800,000.

“This is an extraordinary effort by our volunteer citizen scientists,” said ADEQ Water Quality Division Director Trevor Baggiore. “By working together, we can ensure that our rivers remain healthy and vibrant for generations to come.”

As one of Arizona’s two wild and scenic rivers and designated by ADEQ under the CWA as one of 22 Outstanding Arizona Waters (OAW), Fossil Creek is a popular recreation destination. Arizona’s OAW are waterbodies that have exceptional ecological, cultural, or recreational value and as such, receive additional protections. Due to the Backbone Fire, public access to the creek was closed from June 2021 to November 2022. This temporary closure provided ADEQ and our citizen scientist volunteers with a unique opportunity to study and sample the creek during a time when people and pets were not allowed in the area. People and pets can contribute E. coli to highly recreated waters in many ways including leaving trash behind, not cleaning up pet waste, and not using designated restrooms to name a few. Volunteers will continue to sample as people return to recreate on the water.

The San Pedro River is the last major free-flowing, undammed river in the American Southwest. The removal of this segment of the San Pedro River from the Impaired Waters List is a result of the joint efforts to restore wildlife habitat and water retention in the lower San Pedro River Wildlife area. The Arizona Game & Fish Department has been actively working to improve the environmental conditions on the San Pedro. Efforts have included working with local mining companies to remove cattle from conservation lands along the river and riparian corridor, and working directly with grazing permittees to reduce access to the riparian corridor.

In addition to the provisional delisting of Fossil Creek and a segment of the San Pedro River for E. coli, Potrero Creek, a tributary for the Santa Cruz River, is proposed to be delisted for dissolved oxygen, but will remain on the Impaired Waters List for E. coli and chlorine levels.

ADEQ will continue to provide training and equipment to sister agencies and volunteers to sample Arizona’s surface waters. The agency encourages everyone to get involved in helping protect Arizona’s rivers. There are many ways to participate, from organizing a cleanup of your local river to downloading ADEQ’s Arizona Water Watch mobile application before visiting one of Arizona’s rivers and sharing with us your photos of the water, even when they are dry. Our scientists use the photo submissions to more quickly discover and analyze water quality issues, update flow data and identify waterbodies for future studies.

Background and Resources

CWA Section 303(d) Impaired Waters List | View >
Arizona 2022 Clean Water Act Assessment | View >
Arizona Outstanding Waters List | View >
Arizona Surface Water Monitoring | Learn More >
Arizona Water Watch Mobile Application | Download >


ADEQ Public Information Officer
602-540-8072 (cell) | Email >