the team decided to directly notify at-risk or involved institutions, including hospitals, of the boil water advisory. the walkerton hospital received its notification at 3:30 p.m. that day. prior to this, and despite numerous contacts with bgoshu staff, hospital personnel had not been aware of potential danger from walkerton water; in some cases hospital personnel had been told specifically that water was not the cause of the outbreak. the ministry of the environment nominally received notification of the outbreak from a message left on the home answering machine of employee philip bye. bye, however, did not recognize the significance of e. coli being present in walkerton water and, believing the measures public health officials had already taken to be sufficient to deal with the contamination, he did not pass the news on to the emergency response arm of the moe that day. in the face of rising community casualties—by the evening of may 21, 270 people had contacted the walkerton hospital after experiencing gastroenteritis symptoms, and one patient had had to be airlifted to london, ontario, for treatment—the situation was being perceived as increasingly serious by most of those involved. that evening, the bgoshu contacted the minister of health and the chief medical officer of health of ontario. requests were placed with the ministry of health for an epidemiologist and for staff to assist in treating walkerton-region gastroenteritis patients; public health staff began looking into acquiring equipment that would be needed to treat any e. coli patients whose infections progressed to hemolytic-uremic syndrome (hus). david patterson ordered further testing of walkerton's water, sending james schmidt to collect samples of water from various sources in walkerton, including "food premises, hospitals, and the health unit office". patterson received schmidt's collected samples and drove them to london overnight. the samples were received by the london regional public health laboratory at 12:45 a.m. on may 22; a further round of sampling was ordered to be done the next day. events of may 22 despite increased awareness of the severity of the outbreak, as may 22 began, some links in the public safety chain were still uninformed as to either the existence of the outbreak or the fact that it presented a real and present danger to public health. mayor david thompson, himself suffering from symptoms of gastroenteritis, which he assumed to be flu, took no investigatory or emergency-preparedness action on may 22, nor did james kieffer, chair of the walkerton public utilities commission (puc), who had been alerted to the outbreak the day before. ministry of the environment (moe) employee philip bye, who had been notified by bruce-grey-owen-sound health unit (bgoshu) phone call the previous evening, did not understand that e. coli contamination was a life-threatening emergency; he took no action until he was contacted again later on may 22 by a concerned dr. mcquigge. at that point, bye sent an environmental officer to join the investigation in walkerton. the moe environmental officer dispatched by bye, john earl, spoke first to david patterson (the assistant director of health protection at bgoshu), who expressed his growing suspicion that walkerton puc water was the source of the contamination; patterson asked earl to obtain further information and records from stan koebel, the puc manager. koebel, in his verbal interview with earl, failed again to provide information about adverse water testing results and other potentially crucial system information; he informed earl that well 7 has had a new chlorinator installed, for example, but omitted mention that this had been after the well had pumped unchlorinated water into the system for days. earl requested and was given documentation regarding well testing, water distribution maps, and pumping history for the wells. included in this documentation were records of the may 17 adverse testing results of may 15 samples from the "highway 9" water main construction; excluded was pumping history for well 7. earl returned to the moe with these documents and reviewed them, noting the may 17 testing results, but notified no one else of these results. after earl left the puc, stan koebel contacted his brother frank to ask him to "clean up" the pumping log for well 7. stan koebel hoped to have a new document to present to earl the next day that would not reflect that well 7 had been unattended to and unchlorinated. frank koebel complied with this request. he destroyed the previous version of the document and created a new one with fictitious data: the new document showed well 7 as not having operated on the days it had actually been pumping unchlorinated water into the system, and contained chlorine residual records for well 7 which were entirely fictitious. frank koebel later testified that he had falsified this document "so it would look better to the moe". while the ministry of the environment investigated the outbreak from the procedural end, public health officials swung into a medical investigation. early epidemiological investigation had demonstrated fairly strongly that infection risk seemed to correlate to physical presence in walkerton—even for patients visiting other area hospitals, investigators typically found that the patient lived in or had visited walkerton during the period of their infection— and investigators now began making telephone calls to patients, gathering information about onset of symptoms, possible methods of exposure, and the patients' personal demographic information. a compilation of data from this secondary investigation demonstrated that most patients had an onset of symptoms within a fairly narrow window of time, with the highest rate of onset occurring on may 17. taking into account the incubation period of e. coli infection, the medical team determined that most patients had been exposed to the pathogen between may 12 and may 14. investigators had less luck trying to pinpoint a physical source of the infection; when affected patients' residences were mapped, their distribution across a map of walkerton showed no immediately apparent pattern, with affected populations present in all areas served by walkerton's water system. by that evening, public health investigators had concluded based on patient interviews and demographic mapping that the water system was the most likely vehicle of infection, despite their not being aware of the corroborating documents that john earl had collected. they began notifying branch offices of the bgoshu of the outbreak and its cause. events of may 23 and 24 the bruce-grey-owen-sound health unit (bgoshu)'s may 22 presumptive conclusion about walkerton's water was confirmed at 8:45 the following morning, when the london regional public health laboratory reported testing results on the water schmidt had collected on may 21 and 22: both e. coli and fecal coliform results had come back positive on the may 21 samples, and though testing was not complete on the may 22 samples, evidence of coliform growth was already apparent. john earl (the ministry of the environment (moe) environmental officer) returned to the walkerton public utilities commission (puc) that morning to continue his investigation. stan koebel, the puc manager, gave him the well 7-related documents that he and frank koebel, the puc foreman, had falsified, and earl began to analyse the documentation he had collected over the past few days. he noted apparent irregularities in the pumping histories of all three wells, as well as unlikely chlorination levels recorded for well 5. he communicated these irregularities to the moe's philip bye, but neither man reported them outside of his own organization. at 9:45 on the morning of may 23, david patterson (the assistant director of health protection at bgoshu) contacted stan koebel at the walkerton puc and informed him of the may 21 test results. koebel, realizing that his attempts to clean the system beginning may 19 had not been sufficient, confessed to patterson that he had been aware of the contamination of walkerton water since may 17. koebel was reportedly "distraught" at this point in the conversation. after ending his call with koebel, patterson immediately passed on the information about the may 15 test results to the chairman of the board of health and to dr. murray mcquigge, the local medical officer of health. shortly after 11 a.m., a press conference was held at the walkerton hospital. led by mcquigge and attended by hospital staff, bgoshu staff, and the media, this press conference was the first reliable report to the public of the existence and causes of an e. coli outbreak in the community. the walkerton hospital hosted a roundtable at 1 p.m. the same day to inform local physicians of proper treatment for e. coli o157:h7-associated gastroenteritis, especially with regard to infected children, who were at increased risk for renal failure due to hemolytic-uremic syndrome. shortly thereafter, bgoshu staff met with the brockton city council in the council's chambers. this meeting was attended by representatives from the ministry of the environment and the public utilities commission as well as of bgoshu and the city council. the attendees of the meeting reviewed what was known thus far about the timeline of the outbreak, discussed what steps could be taken going forward, and attempted to analyse the adequacy of their response to the crisis thus far. moe representative philip bye announced that the moe would be investigating the ways in which walkerton's water system could have become the cause of the outbreak. mcquigge, in response to questions, asserted that he did not believe the public could have been notified with a boil water advisory any earlier than they were; prior to may 21, neither the distribution of hospital admissions nor then-current testing results supported publicly declaring a problem in walkerton. the meeting became heated, with mcquigge urging stan koebel to "come clean", koebel refusing to disclose adverse test results, and mcquigge and mayor thompson exchanging confrontational words as the meeting broke up. mcquigge later claimed that he had urged thompson to "tell the public what you know"; thompson alleged that mcquigge had threatened him if he "blw the whistle on me or brockton". later in the afternoon, thompson and the council convened a private meeting without bhoshu staff to decide their next steps. stan koebel told meeting participants that testing had shown bacteriological issues in wells 5 and 7; though he allowed that well 7's chlorinator had not been functioning properly, he did not disclose that well 7 had in fact been operating without any chlorinator at all. with the input of koebel and steve burns, an engineer with the highway 9 project's consulting firm, it was decided that burns's firm would develop an action plan to remediate the water contamination. on the basis of this remediation plan, meeting participants decided that it would not be necessary to declare a state of emergency in walkerton. despite this declaration, publicizing of the epidemic, and the boil water advisory, local hospitals continued to treat gastroenteritis patients during the last week of may at numbers more than double typical er throughput. hospital staff were forced to take emergency measures, with elective and deferrable treatments redirected to other hospitals and out-of-town medical staff being pressed into service. by may 24, there had been four patient deaths and the walkerton hospital and the bgoshu were playing host to three epidemiologists from various arms of health canada. 27 people had developed hus, a serious and potentially deadly complication of e. coli infection. the full death toll for the outbreak was initially reported as seven, but later revised to six. aftermath while the community attempted to recover from the events of may 2000, anger and blame ran high. on may 25, dr. murray mcquigge had made a public statement saying that in his opinion, dissemination of information to the community had been hampered by lack of disclosure of adverse walkerton public utilities commission (puc) testing results, and patient deaths could have been prevented had disclosure been made earlier; by may 29, a $1 billion class-action lawsuit had been filed by community members similarly alleging that local officials had failed in their duty to notify the community. authorities from the ontario clean water agency took over operations at the walkerton public utilities commission on may 25 at the request of mayor thomson. the next day, the ontario provincial police launched an investigation into the causes of the outbreak, followed within days by a coroner's inquest and an environmental investigation. during the outbreak, both stan and frank koebel denied any wrongdoing and firmly held that the