A single positive E. coli test at a monitoring site in July prompted an immediate state-ordered boil-water advisory that the city said was lifted after system-wide retesting found no further contamination.

Terry Lawrence, director of water utilities, told the Parzelsville City Council on Nov. 3 that staff follow a monthly bacteriological testing regimen of 40 sites (10 weekly) and that samples are collected into containers with sodium thiosulfate to neutralize residual disinfectant. He said the first positive result came from a "dead end" portion of the distribution system at 20 First and Johnstone, and the laboratory reported the E. coli result to the city on the following day.

Lawrence said the city immediately resampled adjacent upstream and downstream sites and contacted the Oklahoma Department of Environmental Quality (ODEQ). Resampling produced a positive total coliform result at the original site but negative adjacent samples. Because an earlier sample had tested positive for E. coli, the ODEQ issued a boil order Saturday around noon; additional, system-wide samples returned negative and the boil order was rescinded late Sunday evening.

Lawrence described the investigation and the team's conclusion: "We believe it was an anomaly with the sample station." Staff excavated the station and found debris and a missing rubber cap on the spigot. He said the city suspects a small animal might have entered the spigot and that the sample collection did not operate the station's evacuation tube, which likely left the foreign matter with insufficient contact time with disinfectant to be neutralized before it was placed in the sample bottle.

The city said ODEQ performed a Level 2 assessment and found no deficiencies in the treatment plant or distribution system. Staff have implemented changes including installing protective rubber caps on all sample stations (seven replaced so far, remaining by the end of the week), formalizing sampling procedures (flush both spigot and evacuation line), and replacing seven worn stations. The city also said it will integrate with a mass-notification system managed by emergency management to improve direct public communications in future incidents.

Lawrence named staff who worked through the weekend to resolve the issue and said the communications team and a private lab in Tulsa helped expedite follow-up tests. Council members praised the utility staff for the speed of response and the new precautions.