Concern about water quality issues and invasive plants and animals in Lake Champlain may be new to me, but it has been a concern for New York and Vermont for most of the last century. Both states have built facilities to treat the wastewater and runoff that flows into the lake water. Lake Champlain has three major types of water pollution-excessive levels of phosphorus, localized bacteria, and heavy metals and other toxic chemicals.

PHOSPHORUS
Phosphorus is a naturally occurring nutrient that is necessary for plant growth. It's a major ingredient in many lawn and garden fertilizers. Phosphorus becomes a problem when excessive amounts of it end up in a body of water. High levels lead to increased plant growth and algae blooms like what we paddled through in Missisquoi Bay.
Besides being unsightly and hard to paddle through, algae blooms deplete the oxygen in the water, which hurts native fish species. Algae blooms in Lake Champlain can become toxic. In 1999, three dogs died after drinking an excess of lake water and ingesting toxic blue-green algae. On August 3, 2001, a temporary health advisory was issued in Vermont, warning people to keep children and pets out of the lake.

The three main sources of phosphorus are agricultural runoff, stormwater runoff, and wastewater and sewage discharges. Stormwater runoff occurs when rain or melting snow flowing over roads, parking lots, lawns, and rooftops flows into streams and rivers that feed into the lake. With increased urban and suburban growth around the lake, stormwater runoff is becoming a greater problem for the lake. Although agricultural runoff is still the major source of phosphorus pollution in the lake, acre for acre, developed land contributes three to six times as much phosphorus as farmland does. Wastewater flowing through inadequate or overburdened sewage treatment facilities in the Lake Champlain watershed also contributes to the pollution of the lake, both as a source of phosphorus and bacteria, but recent improvements in wastewater treatment have improved the situation.

And then there are the cows. Vermont is famous for its dairy products and a lot of them come from the Champlain valley. All those cows produce a lot of phosphorus-rich manure. When it rains or the snow melts, nutrients leached from the manure run downstream to the lake. One source of phosphorus pollution-the spreading of cow manure on frozen fields in the winter-has been banned in Vermont, but still continues on the New York side of the lake.

BACTERIA
Increased levels of bacteria in the lake, such as E. Coli, have caused sporadic closures of some swimming beaches. Two beaches, Blanchard Beach in Burlington, Vermont and Essex Beach, New York, have been closed for swimming indefinitely due to elevated bacteria levels. A cleanup operation is in the works at Blanchard Beach. Sources of the bacteria include what are called "point sources"-specific places such as sewage treatment plants-as well as "non-point sources"-such as dog waste.