About three-quarters of all boats launched into Whitefish Lake at City Beach this summer were re-entering after a previous trip to the lake.

All other boats that entered the lake at the same location were previously launched in either Flathead Lake, Hungry Horse Reservoir or other places, according to data compiled by the Whitefish Lake Institute.

The city of Whitefish contracts with the institute to provide staff training and inspection of watercraft entering the lake at City Beach. This summer the visual inspection process included a survey of boat owners.

The goal is to inspect boats for aquatic invasive species, but to also collect data on what type of watercraft are entering the lake and where those boats are coming from, according to Josh Gubits, environmental scientist with the Institute.

“Flathead Lake has curly leaf pond weed, which has not been found in Whitefish Lake,” he said. “Both Flathead and Hungry Horse have flowering rush. That’s one of the bigger threats of boats.”

About 1,000 boats were inspected at City Beach between May and September. Most of the boats, about 74 percent, launching into Whitefish Lake originated from Montana, 21 percent were from Alberta and 5 percent traveled from other places. Many of the boats in the other category came from Washington or California.

“The good news is that most of the boats came from Montana,” he said, but noted all, but three of the states where boats originated from, have a host of different aquatic invasive species. “We’ll look at the data more,” he said.

“We want to look more at where people are coming from and what inspection stations they are coming through before they get to Whitefish.”

City Parks and Recreation staff provided visual inspection of the boat and trailer, and also ask a few questions of the owner before clearing the boat to launch. It’s part of continued efforts to prevent aquatic invasive species from entering the lake. This was the fourth summer recreation staff have been trained to identify AIS.

This summer the city again contracted Whitefish Lake Institute and inspections were stepped up from weekends to seven days per week with a survey of boat owners added to the inspection process.

Aquatic invasive species, including non-native plant, fish, mussels and clams, have become an increasing concern for the negative impacts they can have on lakes and rivers.

In 2012 Boats set to launch into Whitefish Lake were found to have zebra mussel fragments, and in 2011 Eurasian watermilfoil was discovered in Beaver Lake.

Species of concern include Zebra mussels, Eurasian watermilfoil, curly-leaf pondweed and flowering rush, according to Gubits.

The survey also recorded the type of watercraft to pass through the inspection station. There were 202 personal watercraft, 91 pontoon boats and 714 boats.

Gubits said each type of watercraft presents its own challenge in regards to aquatic invasive species.

“Pontoon boats have a lot more crevices for mussels to get into,” he said. “Boats have more standing water for microscopic larvae.”