Invasive zebra mussels have been confirmed in American Heroes Park Pond in Bellevue, an unusual detection in a body of water where boats are prohibited.
City park staff discovered the small mussels on Sept. 8 during routine maintenance.
Because motorized boats are not allowed on the pond, state wildlife officials believe high water from the nearby Missouri River likely carried the invasive species inland.
The pond sits just up the road from Offutt Base Lake, where Nebraska’s first established zebra mussel population was documented in 2006.
Since then, they have been found in the Missouri River, Lewis and Clark Lake, Lake Yankton and Beaver Lake.
Adult zebra mussels are about the size of a pinky nail, "D" shaped and cream colored with black zig zag stripes.
While zebra mussels may be tiny, their impact on aquatic ecosystems is huge.
Each mussel filters about a liter of water per day. Multiplied by thousands, the invasive mollusks deplete plankton and crucial nutrients that native species rely on to survive.
Kristopher Stahr, aquatic invasive species program manager for the Nebraska Game and Parks Commission, described it as starving the ecosystem from the bottom up. All the heavy filtering makes the water unusually clear, but Stahr noted that visual clarity is a sign of trouble.
The deeper sunlight penetration can trigger toxic blue-green algae blooms and allow invasive weeds to take over deep water.
Research from the Institute for Sustainable Development shows native mussel populations typically drop by about 90% within a decade of a zebra mussel invasion.
The shells also present a physical hazard for visitors.
“Zebra mussel shells are extraordinarily sharp,” Stahr said, adding that dead shells that wash onshore often cut the feet of swimmers and waders.
Once zebra mussels get established, removing them is a massive challenge.
“Getting rid of them is basically impossible,” Stahr said.
Eradication succeeds only in rare cases involving small, contained bodies of water. Two Omaha-area lakes, Zorinsky and Cunningham, were successfully cleared after they drained the lakes and froze the mussels to kill them. Stahr said it was one of the few successful eradications in the country.
Chemical treatments using copper sulfate at Offutt Base Lake in 2008 and 2009 failed; adult mussels eventually reappeared.
“The stars have to align for that,” Stahr said regarding the eradication.
Still, Nebraska remains one of the few states in the region without widespread infestations, but the state's resources to monitor public waters are limited.
The risks are especially high for agricultural and municipal infrastructure, where mussels can clog pipes and block water flow.
“Anything that inhibits the ability for that water to move can cause a really, really big problem,” Stahr said.
Despite the threat, the state’s invasive species staff is small.
“Our program only has two full-time employees for the whole state, for all invasive species, for all public waters,” Stahr said.
Since Stahr became program manager in 2020, watercraft inspections have grown from 1,000 to over 8,000 annually, with staff testing roughly 50 lakes a month. Still, covering the entire state is a big task.
“We are kind of trying to hold back a wildfire with a super soaker in a way,” Stahr said, who mentioned that high-traffic locations like Lake McConaughy, Merritt Reservoir, Calamus and Branched Oak carry the highest risk. “More people means more risk.”
Because state staff cannot be everywhere, wildlife officials rely heavily on the public to prevent zebra mussels from reaching new lakes.
“The biggest thing that I will tell the public is we need your help,” Stahr said.
Microscopic larvae can survive in small drops of standing water, so Game and Parks urges boaters and anglers to clean, drain and dry all gear.
“Clean everything off, whatever you’re using, drain it completely,” Stahr said.
Game and Parks recommends drying boats, trailers and equipment for at least seven days before visiting a new body of water. Anglers should also empty bait buckets on dry land. Moving live aquatic organisms between water bodies is illegal in Nebraska.
For state biologists, keeping new infestations at bay is the ultimate goal.
“A good day for our program is everything stays the same as it did yesterday,” Stahr said.
If you suspect you have found a zebra mussel or other aquatic invasive species, you can submit the department's Aquatic Invasive Species form.