Lake Memphremagog - Ecology

Ecology

Like many other lakes, Memphremagog is faced with accumulating phosphorus, sediments, and other pollutants from a variety of sources. In addition, exotic species infestations are a concern, with an existing Eurasian water milfoil population and the potential for a zebra mussel infestation. Since the 1970s, significant efforts have been made to reduce the polluting effects of direct discharges into the lake and its tributaries, and lake quality has improved.

In 1994, a Lake Memphremagog Watershed Association was formed to focus on solving lake and river issues. Testing done in 2008 was unable to determine the cause of excessive nitrogen and phosphorus. In 2010, a study revealed that farms contribute disproportionately to nutrient loads. Although farms have 16% of total land use in the drainage area, they produce 44% of the runoff. Baseline nutrients for a lake are 14 micrograms of phosphorus per liter of water. The lake was measured at 17 micrograms, 18% above normal. Although the acreage devoted to farming has decreased, the retired land has most often been developed, itself a source of runoff.