From early June through early July, dust may be pollen from nearby
pine trees. The pollen might look similar to algae, but pollen is
yellow-green and dust-like and floats mainly on the surface. Eventually
the pollen will become water logged and sink out of sight. An algal
bloom is green to blue-green in color and may be soupy in appearance.
are tiny microscopic plants that are natural components of lakes.
An algal bloom occurs in a lake with high nutrient concentrations
- when one species of algae competes successfully with the other algae
present and becomes so abundant that the water becomes murky.
Most blooms in Maine are either made up of diatoms or blue-green algae.
Diatom blooms usually occur in the late spring or early summer and are less
objectionable than blue green blooms. Diatoms turn the water a bright green or
brown, but do not create the same kind of odors associated with blue-green algal
blooms. Blue-green algal blooms create a greater problem for lake users because
they are subject to concentration by wind and to scum formation at the surface
of the lake and at the shoreline. When these algae die and decompose, the
resulting odor can be very unpleasant.