How Long Has P Been a Problem?

Phosphorus has been a part of Lake Champlain’s environment for millennia. The levels of phosphorus in the Lake began to be a problem when intensive human use of the land began. Clearing of forests released the naturally occurring phosphorus in the 1800s. The use of manure and commercial fertilizers on farms and suburban lawns in the twentieth century increased phosphorus inputs further.

Efforts to monitor the cleanliness of Lake Champlain—including the amount of phosphorus—began in 1990. Since then, phosphorus levels have generally remained level. Most areas of the lake show no trend in the amount of phosphorus present. (see What’s in the TMDL to learn about lake segments)