Battling the bloom

Colin Little of the Lower Thames Valley Conservation Authority discusses how the filtration system on the farm of Louis Roesch filters out phosphorous from the field’s tiling system. The water that winds up in the municipal drain sees a reduction of up to 40 per cent of the phosphorous it originally contains.

Phosphorous reduction efforts continue across region

Experts project the potential for a nasty year for an algae bloom on Lake Erie.

This despite the fact we’ve had a colder than normal spring.

Charles Lalonde, project co-ordinator for the Thames River Phosphorous Reduction Collaborative (PRC), said while the spring was cooler, it was much, much wetter as well.

“We had so many huge rain events that it has probably flushed out more soil particles and more nutrients. It may not be a peak year for an algae bloom, but it’s not going to be a minimal year,” Lalonde said.

He added government predictions, on a scale of one to 10 with 10 being the highest, has this year pegged at between six and seven, whereas last year was a four.

Lalonde said the telling signs begin well before the bloom actually occurs.

“What people tend to say is we have an algae bloom when we can see it. But many, many weeks before, there is a build up. The clarity of the water changes because the algae population is active,” he said.

For example, in a healthy stream, you can normally see the bottom. As the water loses its clarity, the algae is feasting and expanding.

The projects in which Lalonde is involved are designed to help reduce the nutrients that leave farmers’ fields and wind up in lakes and streams. But it is one part of a larger problem, he said.

“We’re dealing with a lot of legacy phosphorous that’s at the bottom of the rivers and in Lake Erie as well,” he said.

Lalonde said farmers have become quite diligent at working to keep the nutrients where they belong – on their fields – as 99 per cent of the nutrients aren’t lost.

But the remaining one per cent, in as fertile a landmass as what surrounds Lake Erie, adds up.

“As a farmer, you are more than 99 per cent efficient in your use of fertilizers. That small amount that you would lose per acre is difficult to garner, but when you factor it over millions of acres, it becomes significant,” he said.

The PRC is attacking the issue from several directions.

“We’re developing and testing various ways to mitigate phosphorous loss through the drainage system. Others are looking at how to introduce best-management practices to limit soil erosion. All of these efforts are being introduced to try to mitigate a very small amount of fertilizer that is lost,” he said.

Most of what is lost occurs in late fall and through the winter. Lalonde said the loss is typically associated with extreme weather events.

Lalonde credits local farmers with being proactive in the phosphorous fight.

“The farming community is working with the drainage industry, with cities, with conservation authorities and with environmental groups to see if we can address the water issue that is leaving the farms.

One test site is on a 25-acre field owned by local farmer Louis Roesch. Last summer, a phosphorous reduction and monitoring system was added to the tail end of the tiling system. The water that came off that field went through the filtration system before entering the adjacent municipal drain.

The system features two holding tanks, a catch basin, and two automated and programmable water testing stations. After a heavy rain, the runoff flows into the first holding tank, where it is filtered through mulch and Phoslock – a patented phosphorous-locking technology. It goes into the second tank and through the same filtering process before slowly draining into the catch basin. From there it is discharged into the municipal drain.

Colin Little with the Lower Thames Valley Conservation Authority said the filter is designed to help achieve the goal of 40-per-cent phosphorous reduction as outlined in the Lake Erie Action Plan, a joint initiative of the Ontario and federal governments.

Lalonde said over the next couple of years, the partners on the PRC will be looking at all the testing and generate results to see what is the most effective form of reduction.

Even with the reduction effort, he pointed to the fact there is already a significant amount of “legacy” phosphorous in our watershed. Nasty summer storms only serve to stir things up.

“It’s the violent storms – not only do they do damage to the lakeshore properties, but the huge waves keep churning up what’s in the bottom of the lake and re-suspending it,” he said. “And that’s what the algae needs to get a fresh dose of phosphorous to support their growth.”

Lalonde said farmers are also working to limit soil erosion by using more cover crops for the winter, as well as leaving crop residue on fields over the winter rather than plow it under.

That is obvious in Chatham-Kent where many cornfields see the stalks left in place after harvest.

“Our farmers are aware wind and soil erosion costs them money. They can’t continuously lose soil to erosion,” he said.

The Thames River PRC is led by the Ontario Federation of Agriculture and the Great Lakes and St. Lawrence Cities Initiative.

This project is funded through Environment and Climate Change Canada’s Great Lakes Protection Initiative and through the Canadian Agricultural Partnership, a federal-provincial-territorial initiative. The Agricultural Adaptation Council assists in the delivery of the Partnership in Ontario.



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