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Chemically Treating Weeds

McCook Lake has seen an increase in weed growth in the past few years. There have three troublesome weeds. One is called Sago Pond Weed. This weed is common to lakes, but has not been seen in McCook since the dredging. This weed is an early growth weed and can be seen as early as late May. There also a leafy floating pond weeds which also are causing problems. These weeds start their growth early as well. Although these two weeds are causing problems, the state does not consider them an invasive weed and they will not treat the lake for them. In early July we had been seeing a new weed to the lake called Brittle Naiad. This weed is considered an invasive weed and is not wanted in the lake by state and local authorities. The last two summers the state did spot treat the lake for Brittle Naiad but their efforts will not control the excessive growth seen throughout the lake. They will only treat what they can see, which means the weed is already 4’-5’ tall before it is being treated.

This year McCook Lake residences applied for state permits to chemically treat the water. There have been 45 permits granted. The water cannot be treated without a permit. The Lake Association of McCook Lake has purchased the chemical for those who have received a permit.

Chemical treatment of McCook Lake began on June 17^th and continued through the end of June.

Invasive Asian Clams Found in Lewis and Clark Lake

Numerous Asian clam shells have been found at Lewis and Clark Lake, indicating a high likelihood that the invasive species is established there.

Asian clams, an aquatic nuisance species, were earlier detected in the Missouri River only below Gavins Point dam in Yankton, Clay and Union Counties.

The clams are native to Southeast Asia and were first reported on the West Coast about 1930. They have since spread to 39 states, including South Dakota.

Although often confused with more well-known zebra and quagga mussels, Asian clams do not have threads to attach to surfaces. Asian clams have small (1.5") oval, brown-to-black shells with distinctive, elevated concentric ridges. They prefer shallow, still water with sandy bottoms.

Asian clams are a prolific and highly competitive species capable of rapid growth, and they can displace native species and alter food chains. They can also have an adverse economic impact by clogging water-intake pipes,
damaging boat engines, and affecting drinking water, aquaculture and irrigation facilities.

Asian clams release free-swimming, live young that can be easily transported and spread through the movement of water and equipment from infested bodies of water (the likely means of the most recent spread in South Dakota).

Boaters and others are urged to take the necessary precautions to prevent the spread of the nuisance clams into additional waters in South Dakota.

Before moving among waters in the state:
1. Inspect and remove aquatic plants, animals and mud from boats, trailers and gear.
2. Drain water from livewells, bilges, and transom wells. Tilt motors down to allow lower units a few minutes to drain. Remove all drain plugs and leave out until the next launch.

After the completion of a trip:
1. Pressure wash (>140° F, 3000 psi; can use carwash) trailers, boat hulls and all interior surfaces that may hold water and all gear; direct a constant flow of hot, soapy water into lower units and rinse.
or
2. Leave boats and gear in the open to dry for at least five days after cleaning with soap and water (hot if possible).

While new clam infestations are not good news, effective response is dependent on early detection. Please report any aquatic nuisance species sightings to: Andy Burgess, Aquatic Biologist, South Dakota Department of Game, Fish and Parks at
(605)-773-2743.       
-GFP-