Water Wool or Pithophora
Water wool, or "green cotton-ball algae" as it is sometimes called, can cause tremendous problems in freshwater ponds. It is commonly found around small ponds, slowmoving streams, and canals. Water wool algae usually become a problem in summer when dense growth can interfere with fishing, deplete oxygen, provide a favorable mosquito breeding site, and give the water an undesirable color. Heavily infested ponds can remain a problem throughout the year, especially if the fall and winter months are mild.