Phosphorus is a naturally occurring element, essential to all lakes’ aquatic plant growth at the correct concentrations. Too much phosphorous is a problem for water quality. It comes into our lakes from natural and human sources including:

• Rain. The largest source of phosphorus in our lakes comes directly from particles in the rain.
• Lawn fertilizers.Runoff from fertilized lawns, gardens, and other green spaces carries phosphorus into storm drains and runoff from shorelines runs into the lake.
• Leaves raked or blown into the lake are like brewing phosphorus tea.

• Runoff that includes runoff from roofs, improperly disposed of pet waste, pesticides, chemical and other pollutants (e.g., improper paint disposal, paint chips, household chemical uses)

• Soil erosion.Soil naturally contains phosphorus, and runoff from bare soil containing phosphorus-packed particles will wash into the lake.Erosion from construction sites, eroded shorelines from boat waves, and other disturbed land can negatively impact water quality.

• Road and highway runoff: Runoff from roads and parking lots can contain harmful phosphorus and salts from vehicle use.

Excessive phosphorus can lead to:

• Algae blooms: Increased plant and algae growth reduces water clarity and clogs waterways.
• Decreased oxygen: When algae decompose, they deplete the water of dissolved oxygen, which fish and other aquatic life need to survive.
• Fewer fish: The shift in the aquatic food web caused by excess phosphorus ultimately results in fewer fish and fish predators.
• Impacts to recreation and swimming