What’s with the lake?
If you’ve seen a green covering over Sharon Lake, it’s not algae; it’s duckweed, one of the smallest flowering plants in the world. This plant is taking advantage of the nutrients from the sediment at the bottom of the lake. What is duckweed?
Common duckweed is a vascular plant that is oftentimes mistaken for algae. It isn’t one solid mass either; all of the duckweed floating atop the lake is made up of millions of individual plants. You can see each plant’s leaf floating on the water’s surface, while a simple “rootlet” hangs underwater. An aquatic plant that loves shallow areas of lakes, duckweed takes advantage of the nutrients in the lake sediment give off. Why don’t you get rid of it?
Common duckweed may be one of the smallest flowering plants in existence, but don’t underestimate it; duckweed can double its biomass in as few as four days. Even if Great Parks were to skim everything off the top of Sharon Lake, it would regrow. We also can’t spray any herbicides over the lake, as Sharon Woods Golf Course is irrigated with lake water, and the herbicides would kill the turf on the golf course. Why has the duckweed increased?
Other than duckweed growing so rapidly in just a number of days, the reservoir basin at the lake collects sediment and nutrients from the surrounding watershed over the years. Sharon Lake was dredged in the 1980s, but streambank erosion in the watershed has continued to bring sediment in, and fill the lake over the years. The sediment began accumulating at an unanticipated rate, creating more areas of the lake that are shallow. The shallow areas also provide a source of continuous nutrients that fuel duckweed growth. This abundance of nutrients and shallow spots are what duckweed thrives on. What’s the solution?
Dredging Sharon Lake is the only long-term solution. For more information, please read our feasibility study
If you have a question that is not answered here, please contact our Chief of Conservation and Parks, Bret Henninger
or Director of Natural Resources, Jessica Spencer
, via email or by phone at 513-521-7275.