Canadian Consulting Engineer

Sewage plant blamed for algae problem on Lake Ontario shoreline in Ajax and Pickering

May 28, 2014
By Canadian Consulting Engineer

Citizens and politicians in Ajax and PIckering on Lake Ontario east of Toronto are ramping up a campaign to solve the problem of algae along their waterfront.

Citizens and politicians in Ajax and PIckering on Lake Ontario east of Toronto are ramping up a campaign to solve the problem of algae along their waterfront.

The shorelines in these communities have been plagued with “massive” amounts of smelly and unsightly Cladophora algae in recent years. Now with a provincial election looming, activist groups and city councillors are calling on MPP candidates to pledge to deal with the nuisance — and they are blaming the problem on the Duffin Creek sewage treatment plant.

The Duffin Creek plant services both the Region of Durham, in which the plant sits, but also the Region of York, another large area located to the northwest. York Region is responsible for 80% of the flow going into the plant, which is the second largest in Ontario. It discharges its effluent via an outfall located a kilometre offshore. The plant has been expanded recently and now connects to over 120 kilometres of sewer pipes. A new southeast collector sewer is nearing completion.

The plant’s total effluent is around 340 million litres a day now, but with new housing developments in areas like Aurora, Newmarket and Vaughan, the flow would increase and the expanded plant has the capacity to treat over 630 million litres a day.

The City of Ajax along with groups like Lake Ontario Waterkeeper and PACT POW (Pickering Ajax Citizens Together to Protect Our Water (PACT POW), believe the plant’s effluent is releasing too much phosphorous into Lake Ontario. Ajax Ward 3 Councillor and PACT POW co-chair Joanne Dies writes: “Treated water flowing from the Duffin Creek Sewage Treatment Plant is so high in fertilizer-like phosphorous that a near perfect condition for growing algae is created. All this fertilizer from the Duffin Creek plant makes the Ajax waterfront virtually an algae grow-op. This smelly algae issue negatively impacts residents’ enjoyment of the waterfront and hurts tourism.”

PACT POW would like the plant to include tertiary treatment to reduce the phosphorous in the plant’s effluent, arguing that affordable technologies are available. They also point out that York Region is considering using tertiary treatment for a new sewage plant that will release into Lake Simcoe.

Paul Kuebler, P.Eng., co-chair of PACT POW, says that while the Duffin Creek plant does meet the Ministry’s regulations, the regulations date from 1994. He says that while the plant is currently releasing between 0.6-0.8 mg/l phosphorous per litre of effluent, PACT POW would like that reduced to only 0.02 mg/l.

The Region of York’s website’s says that the plant’s effluent is not responsible for the algae problem. They cite a 2005 study that found Canada Geese droppings were to blame. They also point out that algae are caused by “overland storm run-off, storm sewer discharge, and agricultural run-off.” Zebra mussels, they say, are another factor as the creatures clarify the water, allowing more sunlight to promote the algae’s grown while the mussels’ decaying remains provide the plant with nutrition. Another factor causing the algae may be warmer temperatures in the lake.

John Presta, P.Eng., director of environmental services with the Region of Durham, says that studies that show the plant is responsible for 97% of the phosphorous in the lake water are “flawed.” He points out that Lake Ontario is a huge body of water and “very dynamic,” and other parts of Lake Ontario without sewage treatment plant outlets also have problems with algae. Adding tertiary treatment to a plant when you are dealing with a body of water at such a scale “is not going to solve the problem,” he says.

The Duffin Creek plant is “one of the best performing plants compared to others,” says Presta, who participates in the Canadian National Water and Wastewater Benchmarking Initiative every year.

Currently the plant’s outfall is in the process of a Class Environmental Assessment, with CH2M HILL acting on behalf of the Regions. PACT POW and the other groups want the province to order a more rigorous Individual Environmental Assessment of the outfall.

Whatever the cause of the algae, it’s evident that the problem is real and reportedly even clogged intakes to the Pickering nuclear power plant.

A recent poll of Ajax-Pickering voters indicated that 84% of the residents agree that the region needs to stop the release of phosphorous into the lake.

To find out more about the Duffin Creek Water Pollution Control Plant (WPCP) in Pickering, click here.

To see the “Save Our Waterfront” campaign by PACT POW, click here.


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