Reducing phosphorus loads to Lake Simcoe and south-eastern Georgian Bay

The column charts present estimates of the annual amount of phosphorus prevented from entering the Lake Simcoe and south-eastern Georgian Bay watersheds. For Lake Simcoe, an estimated 27 800 kilograms of phosphorus was diverted from the lake between 2008 and 2017. For south-eastern Georgian Bay, an estimated 5700 kilograms of phosphorus has been prevented from reaching the bay since 2013.

Note: Numbers may not add up due to rounding.

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The amount of phosphorus reaching Lake Simcoe and south-eastern Georgian Bay is reduced through the following measures:

• stream bank erosion is controlled
• livestock are stopped from directly accessing water course
• manure is properly stored
• trees and plants are planted along river corridors
• milk-house washwater is contained
• stormwater ponds are upgraded
• wetlands are restored or new ones are built

The target for both Lake Simcoe and south-eastern Georgian Bay is to put projects in place to reduce phosphorus loading by 2 000 kilograms of phosphorus per year by 2017.

Lake Simcoe is the largest lake in southern Ontario outside of the Great Lakes. Located north of Toronto, the lake is a major recreational area. It is surrounded by productive agricultural land and supplies drinking water to 8 municipalities. Rapid population growth, urban development, and fewer, but larger, farms with more crops and livestock have resulted in elevated phosphorus levels in the lake, causing oxygen concentrations in the lake to fall to levels that are too low for fish to survive. They are also causing overall water quality in the lake to deteriorate. Scientists estimate the annual phosphorus loading rate for the lake has more than doubled to 77 tonnes of phosphorus per year^{Footnote 1}  since the major period of settlement and land clearing that took place around Lake Simcoe in the 1800s.

Similar to Lake Simcoe, excessive inputs of phosphorus are putting stress on water quality and ecosystem health in sections of south-eastern Georgian Bay. Phosphorus in runoff from small urban developments and rural areas are contributing to nuisance and toxic algal growth in the bay. The area includes the United Nations Educational, Scientific and Cultural Organization (UNESCO)-designated Georgian Bay Biosphere Reserve.

The work to reduce phosphorus loads to Lake Simcoe is being led by the Province of Ontario, working with partners such as the Lake Simcoe Region Conservation Authority, local stakeholders, municipalities and other partners. Environment and Climate Change Canada's Lake Simcoe / South-eastern Georgian Bay Clean-Up Fund contributes to Ontario's overall goals to reduce phosphorus in the lake by providing funding for priority clean-up projects at the community, lake-wide or watershed-wide level.

Data for all beneficial management projects funded and completed between December 2008 and March 2017 are included. The year associated with a project reflects the year the project was initiated, not the year the work was done.

The Lake Simcoe Clean-Up Fund (April 2007 to March 2012) and the Lake Simcoe / South-eastern Georgian Bay Clean-Up Fund (April 2012 to March 2017) funded 193 projects designed to reduced phosphorus loading to the two lakes. Of these, 80 projects had a direct impact on phosphorus loading through point-source phosphorus removal. Another 113 projects had an indirect impact through non-point source phosphorus removal and/or aquatic habitat restoration or creation (Table 1). This indicator only reports on projects that resulted in phosphorus reductions to Lake Simcoe and south-eastern Georgian Bay watersheds.

Note: n/a = not applicable.
Source: Environment and Climate Change Canada (2017) Lake Simcoe / South-eastern Georgian Bay Clean-Up Fund Office.

Estimates of reductions in phosphorus loading to Lake Simcoe and south-eastern Georgian Bay resulting from the implementation of beneficial management practices were calculated by either the Lake Simcoe / South-eastern Georgian Bay Clean-Up Fund program or its partners.^{ootnote 2} These estimates were generated using performance measurement data provided in the final reports of all projects receiving funding. These data were then applied to phosphorus-loading equations taken from the scientific literature. These equations are used by other water management agencies in Ontario to estimate the amount of phosphorus removed though management practices. Projects were grouped into 3 source types:

• research and monitoring
• non-point source phosphorus removal/habitat restoration
• point-source reduction

Research and monitoring projects do not result in phosphorus reductions and are not included in reporting.

In general, the amount of phosphorus reaching a watercourse is based on factors including sediment load, form and chemical nature of the phosphorus compounds, soil pH, soil texture, soil type and aerobic conditions. Beneficial management practices to reduce phosphorus inputs include limiting livestock access to streams through fencing, providing alternate watering sources, reducing/controlling run-off from fields, decreasing storm water run-off from parking lots and other hard surfaces, controlling erosion in ditches, and restoring wetlands to buffer stormwater flows.

Once a stewardship project is completed, its impact of removing phosphorus from water running off the landscape is expected to continue into the future. The reduction associated with the project is accounted for yearly. Loading reductions from beneficial management practices completed over the life of the program add to projects initiated since 2008 in the Lake Simcoe basin and 2013 in the south-eastern Georgian Bay basin. In this way, the reductions in phosphorus runoff due to stewardship projects aggregate on the landscape.

Given that the results are estimates, the figures for the total of each project type were rounded and these rounded figures were summed to produce the final number.