Pollen on the water will most often occur in the spring when trees are flowering. Rarely do trees flower in midsummer or fall. Some surface algae blooms - scums will occur in spring such as that by Chlamydomonas which is a rich green color. Dense accumulations of pollen comes from flowers of leafy trees or evergreens, both produce pollen. Pollen will usually be a more yellowish, browinish, or pale dull green color whereas brighter green hues and reds will often be an algae. Exceptions occur. Only way to know if it is pollen or algae for certain is to look at it with a microscope as noted by J.Grey.
Last edited by Bill Cody; 02/22/13 09:27 PM.
