Filamentous algae, also known as pond scum, are a common, harmless aquatic plant that like to grow in shallow, clear lakes and ponds. Filamentous algae are a large collection of various species of single-celled algae. Filamentous algae form on sediment or on underwater objects, like rocks, that are near shore. Algae commonly form in shallow and clear lakes where sunlight can easily reach the bottom of the lake. The algae grow in long chains and form visible strings, or filaments, of algae. The filaments of algae can intertwine and form thick mats that resemble wet wool. Mats of filamentous algae commonly float to the surface of lakes and ponds which can be visually unappealing.
What can you do?
Filamentous algae are not necessarily good or bad for wildlife or water quality. Removing filamentous algae can be done by skimming the surface of the water. However, they best way to reduce algae growth is to limit the amount of phosphorous that enters the water. Phosphorous is a nutrient that fuels algae growth, and it commonly enters waterbodies through storm drains. The best way to reduce phosphorous input is to sweep up the leaves, grass clippings, and fertilizer from your driveway and street and properly dispose of these pollutants. Learn more about keeping storm drains clean here.
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