Backgrounder: Phosphorus Reduction Strategy

Ensuring the Long-Term Health of Lake Simcoe

Phosphorus is a naturally occurring nutrient that all living things need to grow.  However, too much phosphorus in the lake leads to excessive plant growth.  When these plants eventually decay they deplete oxygen levels that aquatic life need to thrive.

Although there is more oxygen available now than there was 30 years ago, the oxygen content in the deep, cold parts of the lake is still too low to allow Lake Simcoe's coldwater fish community to sustain itself.

Aggressive actions are needed to protect and restore the lake's ecological health through reductions in phosphorus and other pollutants.  To accomplish this, the province is launching the phosphorus reduction strategy to reduce phosphorus from the current level of 72 tonnes per year to 44 tonnes per year.

Phosphorus Reduction Strategy

The phosphorus reduction strategy is a long-term (35 years), phased approach for identifying and reducing major sources of phosphorus entering Lake Simcoe and its watershed.

The strategy adopts a watershed approach to reducing phosphorus with the goal of achieving reductions from each major source of phosphorus including:

• sewage treatment plants
• stormwater runoff from urban areas
• atmospheric sources of phosphorus such as dust and windblown erosion
• runoff from rural and agricultural areas
• agricultural polders such as the Holland Marsh
• private septic systems located close to the lake

The strategy sets a deep water dissolved oxygen target of 7 mg/L.  This level is required to support a naturally reproducing and self-sustaining cold water fish community.  Based on current science this target translates into an annual phosphorus load of about 44 tonnes per year or about 40 per cent less than the current load.

To ensure the province meets its long-term objectives for the Lake Simcoe watershed, the phosphorus reduction strategy will incorporate new scientific knowledge, best practices and innovative design and technology as they become available.

This approach will allow the phosphorus reduction strategy to evolve and adapt over time.

Lake Simcoe Protection Plan

The phosphorus reduction strategy is a key part of the Lake Simcoe Protection Plan that came into effect on June 2, 2009.   Building on consultation with citizens and expert advice from scientists, this plan sets a new standard for environmental protection of a watershed and provides a roadmap for helping to restore and protect the health of Lake Simcoe by:

• promoting immediate action to address threats to the ecosystem, such as excessive phosphorus in the lake
• targeting new and emerging causes of stress to Lake Simcoe such as invasive species and climate change.

This science-based, ecosystem approach considers cumulative impacts.  It recognizes that a healthy environment is the cornerstone of healthy communities and a healthy economy.

Implementing the Lake Simcoe Protection Plan

Of the 119 policies in the Lake Simcoe Protection Plan, which marked its one year anniversary in June 2010, 88 were required to be completed in the first year. All have been implemented or implementation is ongoing. A report card (PDF) gives an update on each policy in the plan. Some of the highlights include:

• establishing the Lake Simcoe Science Committee and the Lake Simcoe Coordinating Committee to provide guidance and expertise on the protection efforts

• releasing a discussion paper on the actions that could be taken to protect the threatened shoreline

• consulting on a feasibility study for using water quality trading to help reduce phosphorus levels in the lake and watershed

• releasing the Lake Simcoe Water Quality Report, providing baseline information from the past 29 years of water quality monitoring of the lake

• implementing a state-of-the-art fisheries and aquatic biodiversity monitoring program

• supporting stewardship activities by promoting the development and implementation of:
• best management practices for farmers and the agricultural sector
• individual actions by local residents and cottagers.