Tres Rios Wetlands Prescribed Burn Planned for October

The City of Phoenix, in coordination with the Arizona Department of Forestry and Fire Management (DFFM) and the Phoenix Fire Department, is planning to conduct a prescribed burn at the Tres Rios Wetlands in October 2025. The burn is tentatively scheduled for Tuesday, Oct. 7, but that is subject to change depending on the weather conditions and other factors. The event is expected to produce a significant smoke plume visible in southwest Phoenix and the surrounding areas, and 91st Avenue will be closed from the 91st Avenue Wastewater Treatment Plant North Gate to Baseline Road from 8 a.m. to 4 p.m. 91st Avenue may open sooner if safe to do so.

The primary purpose of the operation is to reduce dense vegetation and is part of the ongoing process of restoring vital riparian habitat. Fire is nature's way of providing nutrients to the soil, removing invasive species of plant life, and improving the overall health of an ecosystem.

Why is Burning Necessary?

Previous attempts to mechanically maintain Tres Rios vegetation have proven to be time-consuming and cost-prohibitive. After researching alternative methods, the Phoenix Water Services Department identified prescribed burns as an optimal means to maintain the wetlands. Additionally, a prescribed burn reduces hazardous fuels, protecting surrounding communities from extreme fire.

Why is the Burn Planned for October?

Per the United States Fish and Wildlife Service Tres Rios Safe Harbor Agreement, prescribed burns may be conducted from October through February to avoid impacts during the breeding season. October is considered the optimal time for the Tres Rios Prescribed Burn; however, the schedule may shift based on weather and other conditions. As winter progresses, the Maricopa County Air Quality Department typically issues more "No Burn Days," which makes scheduling the burn increasingly challenging later in the season.

How Big is the Burn Area?

One entire Tres Rios Flow Regulating Wetland (FRW) cell is allowed to be burned annually. The prescribed burn will target FRW-1, which is approximately 110 acres in size, as identified in the figure below. See the map below of the actual planned burn area.  

How Will the Fire Be Extinguished?

After the prescribed burn is completed, a water truck will spray the perimeter of the cell to extinguish any smoldering flames. Water quality will be monitored and confirmed acceptable before the release of water from the cell to the Tres Rios Overbank Wetlands. That will include allowing sufficient time for any fire debris to settle out and completion of a water quality sampling plan.

What is the Phoenix Fire Department's Role?

The prescribed burn will be led by the Arizona Department of Forestry and Fire Management (DFFM), with the Phoenix Fire Department and City partners providing ignition, holding, and training support.

The prescribed burn will also serve as a training opportunity for the Phoenix Fire Department's Wildland Urban Interface program, which will provide Phoenix firefighters with the necessary skills, certification, and experience to battle wildfires that threaten the City of Phoenix. In addition, the prescribed burn may also give the Phoenix Police Department's Firebird helicopter crew a training opportunity.

The specific training will be focused on the following certifications necessary to coordinate and fight wildfires safely and effectively:

• Wildland Firefighting 1 and 2

• Wildland Engine Boss

• Strike Team Leader

• Task Team Leader

• Incident Commander Type 4

• Burn Boss

• Drone Mapping and Incident Command integration training

Who is Involved with the Prescribed Burn?

In addition to the Phoenix Water Services Department, Phoenix Fire Department, and Arizona Department of Forestry and Fire Management, there are other relevant parties and agencies that may have an interest in the Tres Rios prescribed burn:

• United States Fish and Wildlife Service (USFWS)

• United States Environmental Protection Agency (EPA)

• Gila River Indian Community (GRIC)

• Maricopa County Air Quality Department (MCAQD)

• Arizona Department of Environmental Quality (ADEQ)

• Phoenix-Goodyear Airport

• Sky Harbor International Airport

• Arizona Public Service (APS)

• Salt River Project (SRP)

• Emergency 911 Call Center

• Residents and other stakeholders

What are the Tres Rios Wetlands?

The Tres Rios Wetlands receive reclaimed water from the 91st Avenue Wastewater Treatment Plant and are maintained by the City of Phoenix Water Services Department.

The Tres Rios Environmental Restoration project involves the rehabilitation of nearly 700 acres in and around the Salt River, restoring a vital wetland and riparian habitat. It consists of the Tres Rios Flow Regulating Wetlands (FRWs) and Tres Rios Overbank Wetlands (OBWs). They are located just west of 91st Avenue, south of Broadway Road. The Tres Rios FRWs receive treated wastewater from the 91st Avenue Wastewater Treatment Plant and act as the final polishing step in the treatment process. Reclaimed water is then discharged from the FRWs to the OBWs before being conveyed back to the Salt River. The Tres Rios FRWs are closed to the public. However, the Tres Rios OBWs are open to the public through a free access permit system.

The lush and scenic Tres Rios is now home to more than 150 species of birds and animals like muskrats, raccoons, skunks, coyotes, bobcats, and beavers. The beautiful cottonwood groves, willows, mesquites, and other desert shrubs around the reed-lined ponds and along the trail attract many migratory and wintering songbirds.

Media Access:

Members of the media interested in covering the event should call or email the media contacts listed below for guidance on how to access the area. Fire experts will be available on-site for interviews. For safety reasons and to avoid disruptions to operations, we kindly ask that no drones be flown in or around the prescribed burn area.

Media Contacts:

Michael Gertzman
Senior Public Information Officer
Phoenix Water Services Dept.
602-534-1209
michael.gertzman@phoenix.gov

Capt. Rob McDade
Phoenix Fire Dept.
480-216-9712
robert.mcdade@phoenix.gov