If you believe time wasted at the lake is time well spent, summer is your season. But if you head to the lake in late June or July, an abundance of weeds can put a snag in your plans. According to district conservation officer supervisor, Jamie Pekelder, algal blooms occur as the water warms and facilitates their growth. Pekelder says, “On Big Stone Lake in particular, there is an invasive form of vegetation called curly-leaf pondweed, which runs from the north end of the lake to about the Shady Beach area.”
Although this vegetation is considered a nuisance by swimmers, boaters, and anglers, it has acquired some fans.The curly-leaf pondweed creates prime cover area for small fish. The fish feed on what lives amongst the weeds, and the young feed on the plankton and attach to the weeds. Curly-leaf pondweed’s leafy cover also hides bait fish from predators and provides hideouts for predator fish such as the northern pike to ambush their prey. Blue gills are believed to have a better survival rate due to the increased vegetation. Aquatic insects and other invertebrates cling to the submerged plants. Ducks and geese graze on the curly-leaf pondweeds’ leaves and fruits. Too much of a good thing, however, is not a good thing.
The weed becomes most noticeable when the plant materials decompose. The extra phosphorus acts as a fertilizer and the water looks as though it has been painted blue-green. Eventually, the vegetation binds with the scum, and by the end of July, it settles out to disappear by August.
Where did curly-leaf pondweed get its start? The plant is native to Eurasia, Africa, and Australia and most likely arrived along with the common carp when it was intentionally introduced into midwestern waters as a game fish in the late 19th century. With a lack of parasites and disease common to its original habitat, the plant flourished. Curly-leaf pondweed was first detected in Minnesota around 1910 and in South Dakota in the 1960s and 70s. Adding to its hardiness, is its ability to overwinter under the ice and snow.
Unfortunately, curly-leaf pondweed loves to travel and easily hitchhikes in boat bilges, boats, and trailers only to pitch a tent in new waters. In South Dakota it has spread to three Missouri River reservoirs, Angostura Reservoir, Sheridan Lake, Canyon Lake, Stockade Lake, Herrick Lake, McCook Lake, Lake Mitchell, Lake Alice, Roy Lake, and Big Stone Lake.
If you are a boater, you can’t always avoid picking up this bad boy, but you can help slow its spread. Inspect your boat for plants and remove them before entering another body of water.