Sunset Beach in Vancouver and Snug Cove on Bowen Island remain under swimming advisories after the water in those areas was found to have high E. coli counts.
A reading of 200 E. coli per 100 mL or higher can lead to an advisory that the water is not suitable for swimming.
Measuring the amount of E. coli bacteria in the water determines fecal contamination. Swimming in contaminated water can increase the risk of developing illnesses such as abdominal cramps, bloody diarrhea and vomiting three or four days after exposure.
The information is used by either of the two health authorities in the region — Vancouver Coastal Health or Fraser Health Authority — to determine whether there should be a swimming advisory.
Metro Vancouver also monitors False Creek, where the guideline for E. coli is 1,000 per 100 mL, five times higher than at nearby Sunset Beach. The level is higher in False Creek because it is not considered a swimming area where people are likely to come in contact with the water.
Matt Kieltyka, a spokesperson at Vancouver Coastal Health, said False Creek’s location next to Sunset Beach has an effect on water quality.
“False Creek, which is not a designated swimming area, does have higher levels of E. coli, and Sunset Beach could be affected by the tidal movement of water,” he said in an email. “It’s fair to say that can be one of the factors that’s contributing to the elevated levels at Sunset Beach.”
Farida Bishay, superintendent of environmental monitoring for Metro Vancouver, said samples are collected daily between May and September from 113 sites at 41 locations and measured at Metro’s Microbiology Laboratory.
At Sunset Beach that translates into one sample every week and two samples every third week.
“The analysis takes 24 hours, so we want to be able to have results on Friday to report to our health authorities before the weekend,” she said.
The most recent reading at two stations at Sunset Beach at the mouth of False Creek on July 3 showed 548 and 455 E. coli per 100 mL; at Snug Cove on July 5, there was a single reading of 416. Swimming advisories were initially issued on June 27 for Snug Cove, and June 29 at Sunset Beach.
The July 5 readings from three sites in west, central and east False Creek show readings of 41, 80, and 319, respectively, of E. coli per 100 mL.
A recent Metro Vancouver report looking at E. coli found that beaches had swimming advisories for about 50 days in 2018, the highest since 2014 when there were 240 days of advisories.
Determining exactly what causes a high E. coli reading in any one location isn’t easy, Bishay said.
Reasons can include storm water runoff, animal waste, algae blooms, water temperature, and discharge from recreational vehicles, boats, septic tanks, and sewers.
“We’re not consistently better under wet or under dry conditions,” Bishay said.
Metro Vancouver doesn’t test for differences in E. coli between species, she said. There is no way to tell, for example, whether elevated E. coli are from the growing number of Canada geese around False Creek and English Bay.
The high E. Coli counts in 2014 led to the formation of the False Creek Water Quality Working Group and to a study tracking the source of the bacteria. Results are due later this year.
“It is hoped that the information gained from this study will be helpful to better understand the factors affecting recreational water quality in the region and the sources that may have contributed to the elevated bacterial counts in 2014 and 2018,” the Metro Vancouver report said.