The city of Sedona’s Wastewater Department was notified of a sewer spill occurring at the Mystic Hills Lift Station, at 88 W. Mallard Drive at approximately 6:30 p.m. on Tuesday, March 28.

Operators dispatched to the area and determined the cause to be power and equipment failure at the lift station.

The power was restored and the sewage spill was stopped at approximately 8:30 p.m.

The untreated liquid effluent entered a dry wash that discharges approximately 1,000 feet downstream of the lift station into Oak Creek. It is estimated that 22,000 gallons of untreated liquid effluent was discharged.

Upon further evaluation the morning of Wednesday, March 29, the spill that was thought to have entered Oak Creek did not actually flow into the creek due to a debris dam that stopped the flow of the liquid effluent.

The dam appears to have been formed from last week’s flooding.

The untreated liquid effluent pooled with some effluent seeping into the soil. The city will work will Arizona Department of Environmental Quality on proper decontamination of the area including disinfection efforts.

“Any pooling water accessible by a pumper truck was vacuumed out of the wash last night [March 28],” Sedona Director of Wastewater Roxanne Holland said. “The wash was also disinfected with a diluted chlorine solution in the immediate vicinity of the lift station.”

“Because of the remote location and terrain of the wash, it is not possible to vacuum any pooling water further than the general vicinity of the lift station,” Holland said. “To clarify, no solids, toilet paper, etc. was discharged out of the lift station — this was liquid only.

“Large pools of water in the wash were given a dose of chlorine until a very small amount of residual chlorine was detected. This ensures that the chlorine solution removed any bacteria that was in the water. Any chlorine residual in the pooled water will naturally dissipate with sunlight.”

Water quality samples will be collected to verify that this sewer spill did not contribute to Escherichia coli bacteria levels in Oak Creek.

“Water quality samples in Oak Creek were taken upstream and downstream of the wash,” Holland said. “Results should be available by tomorrow evening,” or on Thursday, March 30, after press time.

Water quality results will be posted on www.sedonaaz.gov/sewerspill, once daily testing is complete and testing will continue until the level of E. coli is at or below the surface water quality standard specific to E. coli set to protect public health. Agencies including Arizona Department of Environmental Quality and the U.S. Forest Service were notified of this spill.

The city will continue to keep the community informed as new information becomes available. For sewer spill emergencies, call the city’s sewer emergency hotline at (928) 203-5180.