 And that test does not detect the presence of shinga toxin-producing E. coli. Rookie Crawford is with the Virginia Department of Health. The water samples that were taken last week were the only ones that were tested for the specific strain of E. coli that got people sick. Also, testing for fecal bacteria in the water didn't show concerning levels. But she says the tests are only a snapshot in time, so in lakes, harmful stuff can be there one minute and gone the next. And with so many people who swam in a lake getting sick over the Memorial Day weekend... It is likely that the lake was the source...