In recent surveys, the Minnehaha Creek Watershed District found that zebra mussels are rapidly spreading throughout Lake Minnetonka.
The district said Wednesday it found zebra mussels -- a particularly destructive non-native mollusk -- at most testing sites across the lake.
Without staff from the state Department of Natural Resources available to inspect boats, zebra mussels and other aquatic invasive species are easily carried from one water body to another.
Zebra mussels were first detected in Wayzata Bay near the eastern end of the sprawling lake last summer. Followup data collected last fall found zebra mussels across much of the eastern half of Minnetonka. This spring, the district placed monitoring devices at 32 sites all over the lake as part of a three-year study.
During the first monthly check of the devices in late June, zebra mussels were found at 26l locations all across the lake, the district said in a news release.
Only five sites turned up no evidence of the invaders, while monitoring devices were lost at three other spots and are being replaced this week.
"It's no surprise the zebra mussel infestation is spreading west across the lake," said Kelly Dooley, a water quality technician with the district. "This invasive species is known for its rapid growth and we're committed to doing everything we can to prevent its spread to other waters, but we need the public's help."
The state legislature stiffened the laws prohibiting transportation of aquatic invasive species, and planned to staff more boat landings with inspectors. As the state government shutdown continues, only a handful of the conservation officers on duty are focusing on safety.
The district reminded people who use Lake Minnetonka and other infested waters to clean, drain and dry their boats and equipment before entering new waters to prevent the spread of zebra mussels.
Minnehaha Creek Watershed District spokeswoman Telly Mamayek said recent awareness campaigns need to be reinforced.
"It really needs to be a habit for boaters to clean off their boats, to drain their boats and their bait buckets, and to allow their equipment to dry at least another five days before entering another water body."
Left unmanaged, zebra mussels will continue to spread, compete with native species, leave beaches littered with sharp shells, damage boats and equipment, and destroy the health of local lakes, rivers and streams.
--- Compiled from MPR and Associated Press reports.