(Council Bluffs) Zebra Mussels have been confirmed in Lake Manawa by the Iowa DNR.
A call from a homeowner at the lake in Council Bluffs about the invasive species led to a DNR investigation. Bryan Hayes, with the Iowa DNR Office in Lewis, says, “We did get a call from a private landowner over there that was seeing these D-shaped clams growing on the rocks. He suspected they were zebra mussels. We did a follow-up look and confirmed Lake Manawa does have adult zebra mussels that were clinging to the rocks.”
Hayes says the extent of the situation remains to be scene. The DNR will conduct additional surveys at Lake Manawa this fall and next summer to monitor the abundance and distribution of zebra mussels. Hayes points out zebra mussel habitat is pretty marginal at Lake Manawa. “They like rock, gravel, and cobble. There is not a lot of that in Manawa. We have some rip-rap to protect the shorelines, but other than that we have a lot of soft sediment in the bottom and it turns to sand in some areas. That’s not good zebra mussel habitat so we predict the population will stay low there which will lessen the impact.”
Large infestations may interfere with aquatic food chains, kill native mussels, clog water intakes, increase algae blooms, and cover beaches with dead shells. Currently there is no effective treatment to control zebra mussels once they have infested a lake. “In the case of Manawa we don’t have any options. We can’t drain it.” He says, “There is no chemical treatment that is practical to do on a water body the size of Manawa.”
The Missouri River was likely the infested water body from which the zebra mussels came. Boaters are reminded to clean, drain, and dry their vessels upon exiting a water body help prevent the spread of invasive species.
