UPDATE June 10, 2014: The illness was due to norovirus, Island Health confirmed, saying it likely came from an infected person who swam in the water.
States the website:
"Contamination of the water will dissipate over a period of time – how quickly will depend on weather and water conditions. Public health staff have confirmed with CRD parks staff that the public washroom at the beach had extra cleaning on Monday and Tuesday, over and above the regular cleaning." Island Health will continue testing the lake's water over the next few weeks.
The agency says it has sent more water samples from the Victoria-area lake to a lab for testing, even though recent tests did not indicate an increase of bacteria.
Island Health says it and the Capital Regional District are investigating other possible sources of contamination, such as a sick visitor.
In the meantime, it's advising lake visitors who are ill not to swim, and others not to drink lake water, shower after swimming and wash their hands before eating and drinking.
The health authority says people should seek medical attention if their symptoms last longer than two days and they show signs of dehydration.