Soil runoff from intense rainstorms can degrade water quality and trigger algal blooms.

Species such as variable leaf milfoil are growing faster and stronger as freshwater temperatures tick up.

Seasonal water layers are lasting longer, helping feed algal blooms from nutrients buried in lake beds.

Maine is home to almost 6,000 lakes and ponds, with some of the cleanest, clearest water in the country. But many are under threat from climate change.