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Insight into Lake's Algae Blooms and Trees Growing in Lake Bed

Updated: Apr 9, 2022

The Glade Run Lake Conservancy often receives questions from community members regarding the lake's algae blooms as well as the trees that still remain in the lake bed, both of which can affect anglers and other recreationists who visit the lake. The following response from Timothy Wilson, Fisheries Biologist with the Pennsylvania Fish and Boat Commission, addresses these two topics and provides insight and understanding for those in our community who may have similar concerns.


Glade Run Lake is a shallow, eutrophic lake. This means there is an abundance (or over-abundance) of nutrients and minerals in the lake's sediments and in the incoming water. Glade Run Lake has a long retention time (i.e., the amount of in-flowing water is quite low compared to the total volume of the lake), which gives the lake a long time to utilize these nutrients to produce abundant vegetative growth consisting primarily of Eurasian watermilfoil (Myriophyllum spicatum), an invasive aquatic plant, and filamentous green algae.

Glade Run Lake was a shallow, eutrophic reservoir before the Pennsylvania Fish and Boat Commission drained it, and draining it hasn't changed that. You might recall that the Eurasian watermilfoil congestion was much worse before the lake was drained compared to what is there now.

Filamentous green algae in Glade Run Lake

One method to reduce aquatic vegetation is to prevent excess nutrients from entering the lake, which the Glade Run Lake Conservancy is working diligently to accomplish. However, there is a considerable amount of nutrient-rich organic material still in the lake bed, so Glade Run Lake will continue to have abundant (and sometimes excessive) aquatic vegetation now and into the future. It is the natural condition of shallow, nutrient rich lakes.

The other vegetation control methods available to the Pennsylvania Fish and Boat Commission (winter drawdowns and/or aquatic herbicides) would not be acceptable to the users of Glade Run Lake, given the recent history of the lake. Also, if we kill the weeds with herbicides, the nutrients will go somewhere and often the result is more algae, so treating one problem can make another problem worse.