How This South Dakota River Became Infested With Zebra Mussels

When the dreaded Zebra Mussel was first discovered in the Great Lakes in the late 1980's, it was almost an inevitability that one day, the invasive freshwater mollusk would make its way into South Dakota lakes and rivers. That day came in 2014, when they were fist discovered in the Lewis and Clark Lake, which borders both South Dakota and Nebraska.

Since then, South Dakota Game Fish & Parks Staff have faced a nearly impossible battle of keeping the devastating pests at bay. Zebra Mussels have since been discovered in Blue Dog Lake, north of Waubay, Pactola Reservoir near Rapid City, and Lake Mitchell, north of the town of Mitchell.

In 2023, the Zebra Mussel was officially found in the Big Sioux River:

While conducting river otter surveys on the Big Sioux River, GFP staff found zebra mussels at two locations. The zebra mussels were detected roughly five miles south of Watertown, and downstream of the connected zebra mussel positive waterbody of Lake Kampeska..

-South Dakota Games Fish & Parks

That raises the obvious question: Now that they're here, likely for good, what are we doing about it?

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In the time since the 2023 discovery, it's been described as an "infestation" of zebra mussels within the Big Sioux River. And while it was widely believed that it was only a matter of time before the first one was spotted within the city limits of Sioux Falls, to my knowledge, that has yet to take place.

With that being said, the mollusk is almost assuredly here already, so how might the city deal with it?

Zebra Mussels pose a big threat to water infrastructure due to their tendency to attach to and clog pipes. If left untreated, this can be a costly endeavor for any city.

Many cities combat these mussels by using preventative, physical, and chemical strategies. For chemical control, cities typically use chlorination (usually sodium hypochlorite), copper-based compounds, or bacterial toxin.

Other ways ways cities deal with an infestation are through filtration (using filters to remove larva), installing resistant coatings, and hot water thermal treatment (spraying pipes with water at 95°F or higher).

While, to my knowledge, the city hasn't publicly commented on what strategies it's using to combat these Zebra Mussels, it's most likely using a combination of the above stated, or, keeping them on standby for implementation.

The fact of the matter is, once Zebra's establish themselves in a large body of water (Big Sioux River), they are generally considered permanent and efforts typically shift to control and management rather than eliminating them altogether. On top of that, a single female Zebra Mussel can produce up to one million eggs per season, making it impossible to completely eradicate them.

Rather than focusing on eliminating them altogether, the strategy for the city of Sioux Falls will now be: System Protection and Damage Control. This means the city will need to continuously use the above mentioned strategies on a regular basis to stay on top of the matter and to prevent degradation of any of the city's water infrastructure.

To get a better idea on how other cities are handling the Zebra Mussel issue and what it may look like for Sioux Falls, check out the YouTube video below.

Story Sources: SD News Website Archives