Filamentous Algae

on Springledge 03/09/12

Area biologists are concerned and warning that there will be an unusual amount of algae coming to the surface of many of the county lakes because of the mild winter.  Shorter ice and snow coverage combined with a shorter time with very low temperatures make for ideal conditions for large amounts of algae to have grown in our lakes over the winter.  As the water warms and the algae produces oxygen bubbles it will come to the surface.  A significant bloom is already visible on the surface of Springledge Lake as shown in the photos below.  This is filamentous algae which is unsightly, but harmless.  The greater concern is that these conditions also promote the proliferation of blue-green algae which is toxic.  To learn more about blue-green algae click on the link below.



Filamentous Algae (Spirogyra, etc.) are long visible chains of single algae cells that form threads or filaments.  The algae grows on the bottom of our lakes in shallow water attaching itself to chara (another form of algae), branches, rocks, docks and bottom debris.    As the water warms unsightly mats float on or near the surface of our lakes as a thick green pond scum.

Filamentous algae is a phytophankton that grows prolifically because of the high nutrient load in our lakes.  The water level o four lakes is maintained only by rain water run-off.  We have no springs or streams inflows.  The storm water run-off from all of the yards, streets, sidewalks and driveways goes into our lakes carrying with it all grass clippings, leaves and excess fertilizer this is not absorbed by our lawns or buffer strips.  Since the majority of commercial fertilizers contain phosphate our lakes are inundated with excessive nutrients. 

Read more on the impact of Phosphorus in Lake County 

Submerged portions of all aquatic plants provide habitats for many micro and macro invertebrates (i.e. bugs, worms, etc.). These invertebrates in turn are used as food by fish and other wildlife species (e.g. amphibians, reptiles, ducks, etc.). After aquatic plants die, their decomposition by bacteria and fungi provides food for many aquatic invertebrates. However, filamentous algae has no known direct food value to wildlife.

McCloud Aquatic Services treats our lakes as needed with an algaecide called copper sulfate.  It is effective in killing the algae and you will see the mats turn brown after being treated.  Copper sulfate if toxic to the lake and accumulates in the bottom mud and muck.  Eventually one time it builds up to harmful levels to the inhabitants of the lake. 

ALL OUR RESIDENTS need to realize that they live in our watershed and that what they do in and around their property directly impacts our lakes causing the algae blooms and the resulting use of chemical to control it.  If all or us would become more environmentally conscious and either stop the use of fertilizer or at a minimum purchase phosphate-free fertilizer it would reduce both the blooms of algae and need for toxic chemicals to treat it.

Phosphorus in Lake County

Blue-green Algae