Highland Lakes

Green algae on a surface of the lake

Lake 5 (Beach 7) and to a lesser extent Lake 3 (East Highland Lake / Indian Lake) have historically experienced the growth of Spirogyra, a green algae mat usually covering the bottom of lakes. This “cold water” algae benefits from sunlight passing through the water column due to increased water clarity during colder months. The conditions experienced this spring have been particularly severe with much of the lake surface covered with this algae which has combined with another algae – Mougeotia. A microscopic examination confirmed the presence of another algae – Mougeotia – present in the floating mats. How does this green algae at the lake bottom rise to the surface?

Spirogyra and Mougeotia are green algae which perform photosynthesis, converting energy from sunlight into energy used to live. These green algae produce oxygen during photosynthesis and it is this oxygen, trapped as bubbles in these bottom mats, which eventually is sufficient enough to break off and float portions of the mat from the lake bottom to the surface.

The Club has received consistent guidance from both Princeton Hydro, LLC and Solitude Lake Management to leave these floating mats untreated, as Spirogyra/Mougeotia mats are host to a diverse population of invertebrates and other organisms quite beneficial to the overall health of lakes. Another benefit is that these mats consume nutrients in the water column denying these nutrients to the more troublesome green and blue-green algae which appear as water temperatures rise. During the week of April 22^nd Lake 5 was inspected by a Solitude representative who affirmed the Club’s initial diagnosis and reiterated that the best approach is to leave this beneficial algae alone for the time being.

As water temperatures rise (of course, temperatures have been below average this past week) and nutrients in the water column are consumed and thereby diminished, past experiences indicate and the expectation is that the surface mats of Spirogyra/Mougeotia will dissipate. Treatments will take place during the week of May 12 if these mats remain. The bottom line is that patience is needed as nature does its job, and we appreciate everyone’s understanding.