State Confirms Zebra Mussels in Lake Sakakawea

North Dakota Game and Fish Department found the invasive mollusks in the state's largest lake for the first time.

Updated on Nov. 7, 2026 in Fishing

Wide view of a calm prairie reservoir under overcast sky, with a weathered dock post on a gravel shoreline and sparse cottonwoods on the far bank. — North Dakota Game and Fish Department confirmed zebra mussels in Lake Sakakawea, the state's largest reservoir, where the invasive species had never been found before. AI Illustration. Upload story photo >

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North Dakota Game and Fish Department detected zebra mussels in Lake Sakakawea, the state's largest lake, where they had not previously been found. Routine water sampling first showed microscopic zebra mussel larvae in the extreme eastern portion of the lake, and divers later located two adult mussels.

Why it matters

Zebra mussels are an invasive species that can spread through boats and equipment, so their presence in a major reservoir raises concerns for the lake and the wider state waters. The department's response will determine whether the population is limited or spreading.

Divers found two adult zebra mussels between the Sportsmen's Centennial access and the Highway 83 embankment, and three crews have searched for more without finding any in follow-up work. Whether the population extends beyond that area remains unresolved.

The players

North Dakota Game and Fish Department

The state agency responsible for managing wildlife, fisheries, and aquatic resources in North Dakota, including monitoring for invasive species.

The details

Water samples were sent to a lab, where personnel look for microscopic larvae called veligers that indicate zebra mussels are present. After the positive sample, Holen and his team entered the water in wet suits to search, finding two adults in the area bounded by the Sportsmen's Centennial access and the Highway 83 embankment.

Summer: the department conducts annual routine water sampling across the state.
Winter 2026-27: the department evaluates watercraft inspection routines and prepares a prevention plan.
2027: the department plans additional water sampling in the original detection area.

Season Trajectory

Zebra mussels have spread across North American inland waters since their introduction in the Great Lakes region, and this detection extends that range into a major North Dakota reservoir. The state's response in 2027 will show whether the Lake Sakakawea population can be contained.

Anglers and boaters on Lake Sakakawea may see increased watercraft inspections as the department evaluates its prevention routines. Boaters moving equipment between waters can help limit spread by following the department's inspection and cleaning guidance.

The takeaway

Early detection and prompt searching have so far found no spread beyond the original area, but continued sampling will determine whether that holds. Anglers and boaters can help protect North Dakota waters by inspecting and cleaning gear before moving between lakes.

What happens next

The department will take more water samples in the original detection area in 2027 to determine whether mussels are spreading, and will evaluate watercraft inspection routines over the winter with possible added inspection presence at the lake.