During the early summer you may see an accumulation of a mustard yellow scum on inland lakes and along the shore and bays of Lake Huron and Georgian Bay.
The scum becomes most visible during the month of June and floats in large masses and accumulates along shorelines and beaches.
The scum is pine pollen and should not be mistaken for algae or spilled paint or petroleum.
It is not harmful and is not a risk to health.
Pollen from evergreen trees usually appears yellow while from some deciduous trees the pollen is sandy brown or gray. The pollen is blown onto water from surrounding forests by high winds. It then drifts, trapping floating algae and other aquatic debris. The accumulation of material that reaches the shoreline is unsightly and can be malodorous when it decomposes. The pollen eventually decomposes or becomes trapped in the sediment along shore.
Reprinted from Ministry of Environment.