Why Are Invasive Species a Threat

• Invasive species outcompete native aquatic species and alter aquatic food webs

• Fewer native plants means less shelter, food and dissolved oxygen for aquatic life

• Once established, invasive plants can spread rapidly, affecting boating and swimming.

Click here to download a copy of LSPA’s informational card on aquatic invasive species.

Curly-leaf Pondweed Found and Removed Again in Lake Sunapee

On June 9, 2025, LSPA brought in two divers to remove invasive curly-leaf pondweed near the Georges Mills boat ramp, where it was first spotted in 2024. About 12 plants were found in three small clusters along one side of a submerged log. We’re confident the divers got all of it, but we’ve scheduled a follow-up dive for early September just to be sure.

Click here to read more.

Spiny Water Flea Found in Newfound Lake

Spiny water flea (Bythotrephes longimanus), a type of crustacean, was discovered in Newfound Lake in September 2025 making it the 3rd waterbody in New Hampshire with this invasive species. It was found in Lake Winnipesaukee and Lake Winnisquam in 2023. Click here to download a fact sheet from NHDES.

Unfortunately, there is no known treatment so the best thing is to prevent it from entering a waterbody in the first place by cleaning, draining and drying boats, trailers and all gear.  As with other aquatic invasive species, spiny water flea can negatively affect the aquatic food web by changing the natural communities and outcompeting native zooplankton species which in turn impacts the fish populations as well. Click here to read a recent article in the New Hampshire Bulletin.