Lake Winnipesaukee water quality in decline, study finds

A new report commissioned by the Lake Winnipesaukee Alliance reveals a steady decline in the water quality of Lake Winnipesaukee over the last 40 years. Data indicates that water clarity has decreased by more than 8 feet during this period.

Scientists identify three primary drivers of this decline: stormwater runoff, septic effluent, and road salt. These factors contribute to increased phosphorus levels, which fuel the growth of algae and harmful cyanobacteria. Cyanobacteria blooms have increased by an average of 23% annually over the past seven years. Phosphorus levels are projected to rise by nearly 40% in the coming decades.

Increased development around the lake has led to more paved surfaces, such as roads and rooftops, which prevent water from soaking into the ground and instead cause runoff to flow directly into the lake. The report suggests that while the lake is at an inflection point, action from property owners, landscapers, and local communities can still reverse the trend and protect the ecosystem.