Phosphorus promotes the growth of algae in lakes.
In excessive amounts, algae can:
• Impair recreational uses
• Impair aesthetic enjoyment
• Impair water supplies
• Impair the biological community
• Produce toxins that harm animals and people
Phosphorus concentrations vary throughout Lake Champlain.
Where phosphorus levels are low, the water is relatively clear and blue.
Where phosphorus levels are high, the water is green and murky with algae.
Phosphorus concentrations in Lake Champlain are higher than the amounts allowed by Vermont’s Water Quality Standards, especially in Missisquoi Bay, St. Albans Bay, and parts of the South Lake. Phosphorus concentrations in Lake Memphremagog are also higher than the amounts allowed by Vermont's Water Quality Standards.
For a map of phosphorus distribution in Lake Champlain, see the Lake Champlain Basin Program's Lake Champlain "Phosphorus Concentrations" page showing phosphorus levels in Lake Champlain between 1990 and 2011.