This spring has been one of the wettest springs in decades. Big snow melts followed by what feels like a never-ending rain shower mean that many communities on the Great Lakes and northeastern Atlantic Coast are flooding.
Toronto is no exception. By May 6, one month’s worth of rain had already fallen on the city. Nearly twice as much rain as usual fell in April.
All that rain is bad news for water quality in Toronto. Our aging sewage system collects stormwater and sewage together. When there is too much rain or snow, it blends with sewage from homes and businesses. That “combined” sewage flows into the closest waterbody, instead of heading to the wastewater treatment plant. The lower Humber, lower Don River, Black Creek, and Toronto Harbour get the brunt of the sewage runoff.
Concerned about boaters in the Toronto Harbour, Waterkeeper monitored water quality near sewage outfalls last summer. We published the results last fall, showing how a handful of sewage pipes are responsible for most of the sewage pollution in the Harbour.
What you didn’t know is that our staff kept going out all winter. They braved ice and snow to check a few locations in the off-season. From January to March, the two locations near Rees street were very clean. Water quality usually met provincial guidelines for protecting and public health and the environment. On some days, we found no E. coli at all.
Then the snow melted and the April rains started falling. The Harbour suffered. As water levels rose, so did bacteria levels.
Pier 4 Marina was hit hard. On April 5, 12, 26, and May 3, every sample collected in the marina had bacteria levels “too numerous to count.” That’s a technical term that means there is at least 300 times more E. coli in the water than government guidelines consider safe. Once we hit that number, it becomes impossible to count individual bacteria colonies—our lab dishes are completely overgrown with bacteria.
The Pier 4 Marina results are the worst we have seen in the year we have been monitoring Toronto Harbour. We have never before collected samples where every single test was above 30,000 E. coli per 100 mL of water.
Harbourfront Canoe and Kayak Centre fared a bit better. On April 5, bacteria levels were above guidelines for swimming and aquatic life, but under government guidelines for boating. Results on April 12 were mixed. April 26 was good, with only one sample having any E. coli. On May 3, during the rainiest week of the year, samples at the Centre ranged from 1,000 to 4,700 E. coli— all above government guidelines.
What’s going on here? We can’t say for sure what is causing the problems at Pier 4 Marina or why water quality is so much worse than at the Canoe and Kayak Centre, just one block away. We did another round of samples this weekend and sent the results to an independent lab for verification. We will share the results as soon as we can.
In the meantime, please use caution around the water for three days after it rains.