e. coli. a subsequent government report concluded that the cattle operation had followed all safety and husbandry best practices with regard to manure storage and use, and that though the e. coli contamination had almost certainly come from the farm's manure usage, the farm's operator was not at fault for contamination of the well. outbreak beginning may 17, 2000, absenteeism in the walkerton school system took an upswing. that day, the walkerton hospital treated seven children suffering from gastrointestinal ailments involving cramping and diarrhea. the illnesses were not initially recognized as part of a pattern, and no report was made to the bruce-grey-owen-sound health unit, which was responsible for public health in grey and bruce counties. on may 18, twenty students were absent from the mother teresa school in walkerton; the next day, twenty-five were, with a further four sent home from mother teresa and eight sent home from the walkerton public school. the increasing number of community illnesses became even more noticeable on may 19, when a pediatrician and a retirement home both reported outbreaks of gastroenteritis among their charges. by may 20, the walkerton hospital had fielded calls from more than a hundred people about incidents of gastroenteritis in the town, and attended to dozens more in their emergency department. attending physicians and health care workers, aware that the gastroenteritis symptoms they were seeing were consistent with possible e. coli infection, began collecting stool samples from affected patients. when public health officials put together common reports, they found that three area hospitals had recorded incidents of patients suffering from gastroenteritis symptoms. walkerton's hospital recorded the highest number of such patients, with at least twenty patients visiting the emergency department with bloody diarrhea on may 20, and two more patients admitted for diarrhea-connected dehydration. hospitals in two neighbouring towns had each seen one case of bloody diarrhea. initial public health response on may 20, early laboratory testing was completed on fecal samples submitted the day before. e. coli o157 was found in at least one sample from the owen sound hospital; when health officials contacted other hospitals in the bruce-grey system, they found that all were handling patients with gastrointestinal ailments consistent with e. coli infection. potential e. coli infection changed the treatment plan for patients reporting to these hospitals or to local doctors; anti-motility medication that would typically be prescribed to patients suffering from diarrhea unrelated to e. coli could in fact exacerbate the condition of patients whose diarrhea was due to e. coli infection, and any patient infected with e. coli o157 was at risk for potentially fatal hemolytic-uremic syndrome. david patterson, the assistant director of health protection at bruce-grey-owen-sound health unit (bgoshu), immediately contacted beverly middleton, a public health inspector in the owen sound office of the health unit, and the two officials began passing along information to local medical facilities about how to properly treat e. coli-based gastroenteritis. later the same day, patterson asked james schmidt, middleton's counterpart in the walkerton health unit, to contact the walkerton public utilities commission (puc) and obtain information on chlorination levels in the water system. stan koebel (puc manager) informed schmidt that chlorine residuals in the distribution system were 0.1 to 0.4 parts per million; based on lack of familiarity with water chlorination, patterson concluded that the presence of chlorine residuals at any level indicated that the water system was free of contamination. he proceeded with investigating other possible sources for the e. coli. throughout may 20, patterson expressed his understanding to community members and other investigators that walkerton's water could not be the source of the outbreak; bgoshu personnel also urged the puc to issue a press release assuring the public of the safety of the water. initial public utilities commission response by may 18, rumours were already circulating that walkerton public utilities commission (puc) water was the cause of the illness increasing numbers of residents were suffering. staff at the puc had also begun receiving calls enquiring as to the safety of town water. on may 19, public health officials contacted the walkerton puc about the possibility of the water system being involved in transmission of the gastroenteritis; they were told that the town's drinking water was "okay". after speaking to public health officials that day, stan koebel (puc manager) began the process of flushing the system and increasing chlorination levels, procedures he described to david patterson as "precautionary". this flushing continued into may 20; koebel's testing records from that day note sharply increased chlorine residual levels, though evidence later indicated that koebel's testing had likely been done improperly and thus returned higher-than-reality chlorination results. the same day, koebel returned well 5, which had not been feeding walkerton's water supply since may 15, to service. the well was then turned off at 1:15 a.m. on may 21. chief justice of ontario dennis o'connor's later report on the event concluded that by may 19, koebel was aware that the may 15 testing of water in the walkerton system had returned results that indicated contamination, and his action to flush the system with heavily chlorinated water from well 7 on may 19 was taken in the hopes of eradicating the contamination before further tests could be conducted. significantly, koebel did not disclose to the health inspectors to whom he spoke on may 19 or may 20 any information about known adverse test results or the fact that he knew well 7 had been providing unchlorinated water to the system from may 15 to may 19. o'connor's report interpreted this not as an act of accidental omission, but as a deliberate attempt by koebel to conceal what he knew to be substandard and potentially unsafe practices in his department. at the same time, however, koebel continued to consume puc-served water and allow his family to do the same with no apparent concern about its safety; o'connor concluded that while koebel knew the system was contaminated, he did not understand that the e. coli bacteria causing the contamination were potentially deadly. christopher johnston: i just want to inquire and find out what's going on, that's all.stan koebel: we had a fair bit of construction and there is some concern – i'm not sure, we're not finding anything ... but i am doing this as a precaution ...christopher johnston: so you haven't had any adverse samples then?stan koebel: we've had the odd one, you know, we're in the process of changing companies, because the other company, it closed the doors, so we are going through some pains right now to get it going. excerpt from may 20th telephone conversation between stan koebel, of the walkerton public utilities commission, and christopher johnston, of the ministry of the environment. on may 20, robert mckay, a puc employee who was on medical leave at the time, anonymously contacted the ministry of the environment's spills action centre (sac) to report potential issues with the walkerton water supply; after observing fire hydrants being used for system flushing, he had concluded that the flushing may have been related to the ongoing illness outbreak in the community and felt that he needed to report his conclusion. mckay also reported to the sac that walkerton water had failed "lab tests", but he was unable to provide detail about what aspect of the water quality had caused the failure. later in the day on may 20, mckay attempted to contact the ministry of health directly about his suspicions, but was unable to get in contact with anyone empowered to handle issues in walkerton; hoping to speed up government response time, he phoned the sac again to report his knowledge that the walkerton puc was using an "unlicensed operator". sac employees, in response to this information, contacted the walkerton puc the same day for information on possible adverse water testing results. stan koebel acknowledged to the ministry of the environment (moe) that "we've had the odd " due to previous construction work but that the system flushing was occurring only as "a precaution". the moe employee who spoke to koebel believed that this meant any adverse samples of walkerton water were in the past, and filed his subsequent report of the conversation accordingly; koebel had again failed to note that he was aware of current test results that showed evidence of e. coli and fecal coliforms. controlling the outbreak events of may 21 morning news reports on public radio on may 21 carried a statement by dr. murray mcquigge, walkerton's medical officer of health, reflecting medical investigators' then-current understanding that walkerton's water system was presumed to be secure and not involved in the outbreak. mcquigge's quoted opinion also characterized e. coli as "unlikely" to be the source of the gastroenteritis outbreak. by 12 p.m. on may 21, however, laboratory results had confirmed enough cases of e. coli o157 in area gastroenteritis patients to merit a declaration by the bruce-grey-owen-sound health unit (bgoshu) that an infective outbreak existed and was being caused by e. coli o157 contamination somewhere. the health unit issued an outbreak number and alerted neighbouring health units of its situation, as well as notifying a variety of walkerton-centred government and management bodies, including the walkerton public utilities commission (puc).1. shortly after the definitive laboratory results were received, mcquigge, representing bgoshu, contacted david thompson, the mayor of brockton, walkerton's parent municipality. according to mcquigge, the conversation involved mcquigge alerting thompson to the fact that community members were falling ill with potentially fatal e. coli infections; according to thompson, e. coli was not mentioned in the conversation and he was left with the impression that the illnesses presented no imminent threat to public health. despite their conflicting memories of the conversation, both mcquigge's and thompson's later testimonies agreed that there had been no request issued that the mayor take action in response to the illnesses; brockton's emergency plan was not put into action, and thompson did not contact any public agencies to seek either information or action. given that the outbreak was continuing and that no reliable information was yet available about the source of the contamination, the bgoshu issued a cautionary boil water advisory (bwa) to the community, to be distributed via local radio stations only. local television stations were not contacted about the advisory, nor was national cbc radio; no paper version of the advisory was distributed to the community that day. local radio station cknx-fm, under the impression that the bwa was cautionary only, reported the advisory at roughly hourly intervals, beginning at 1:30 p.m., rather than more rapidly as they later stated they might have if the import of the announcement had been made clear to them at the time. as a result of the limited distribution of information regarding the bwa, much of the community remained unaware of the boil water advisory until days after its may 21 issuance. around the time the bwa was first being broadcast, david patterson (the assistant director of health protection at bgoshu) contacted the moe's spills action centre (sac) to officially report an e. coli outbreak in walkerton. paul webb, the sac employee taking patterson's phone call, mentioned that they had previously been contacted by an anonymous source (robert mckay) about the quality of water coming out of the walkerton puc. the men discussed the puc's assurances that their water was safe, and the call ended with no action. shortly afterward, however, patterson contacted stan koebel, the manager at the walkerton puc again. koebel expressed dismay at the boil water advisory and the fact that the puc had not been notified of it beforehand. he asked patterson's advice for the best next steps to take; patterson suggested increasing chlorination levels in the system. the same afternoon, the spills action centre contacted stan koebel (the puc manager) directly to discuss the ongoing events; koebel once again failed to mention prior known adverse testing results. in later testimony, he acknowledged that this had been a deliberate omission; the o'connor report concluded that koebel had been hoping that when new samples were collected on may 23, they would test clean and lift the burden from his shoulders. stan and frank koebel again spent part of their day on may 21 flushing the system. at 2:30 p.m. on may 21, the bgoshu convened a strategic response team to handle the outbreak. after discussion,