Isola Bella Passage Blocked

A clearly marked barrier has been installed under the Isola Bella bridge, the latest step to curb the spread of non-native hydrilla. There will be no easy passage for kayaks, canoes, and swimmers this year and probably next. The barrier is not permanent. It will remain in place until hydrilla is under control.

The barrier is modestly lit and employs a bright yellow float to hold it in place. It is designed to keep hydrilla fragments from following the natural current from the northeast cove, where the plant has been found in multiple places, to the northwest cove. This will not impact natural lake rhythms. 

Other measures are being taken in the northeast cove to suppress hydrilla growth as it begins, typically in mid-June. Our thanks go to Russ Conklin and Rich Haupt for their time and energy in placing the “limno” barriers.
An important new paper, posted on the Twin Lakes Association website, and an article in the science journal Invasive Plant Science and Management offer new insights on hydrilla verticillata, also known as water thyme, taking root outside the Connecticut River, including in East Twin Lake.

The article calls hydrilla the “world’s worst” aquatic weed, noting that it “hinders recreational activities by forming dense canopies. If unchecked, it has the potential to displace native species and host a bacterium that produces a neurotoxin implicated in bald eagle and waterfowl deaths.” We highly recommend reading it.
Officials placed boulders at the state boat launch several weeks ago to prevent lakegoers from putting in motorcraft at that location. Unknown individuals moved the boulders aside, presumably to allow boaters to launch there once again. The boulders have since been moved back into place. We ask for cooperation in this matter. The state launch was sanctioned years ago as an entry point for roof-top vessels—kayaks, canoes, and the like. The state restored that status at the request of the TLA. This is to ensure that all motorcraft enter the lake from a single point that we can monitor.
A team of scientists toured the lakes in early May to assess the hydrilla threat and discuss treatment strategies for this year. Several TLA directors joined them. As expected, no hydrilla was found this early in the season. But there was wide agreement that hydrilla will begin to show itself by July.
 Keith Hannon of the Army Corp of Engineers noted that he is running six pilot tests of herbicides in the Connecticut River. Initial data will be available by the end of the year. All the scientists complimented the TLA on its rapid and robust response to hydrilla.
 Remember to submit your photo contest entries. This year’s theme is “colors,” and as always is open to anyone including non-members. Submit by email to or via Instagram #tlaphoto2024. We depend on submissions to generate photos for our website. Please enter often. Two winners will receive $50 prizes and their photos will be featured on the website.

Photos by Grant Bogle

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