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New Hampshire Department of Environmental Services

Media Center

DATE: July 11, 2012
CONTACT: Amy Smagula, 603 271-2248

DES Warns of Expanding Infestations of Exotic Aquatic Plants
Infestations documented at Otter Lake in Greenfield and Naticook Lake in Merrimack

Concord, NH – The New Hampshire Department of Environmental Services (DES) has documented two new infestations of variable milfoil, an exotic aquatic plant, within a week of each other. Both infestations were well-established when found and appear to have been present for at least 2-3 years before being reported. Infestations were newly documented at Otter Lake in Greenfield and Naticook Lake in Merrimack.

Freshwater exotic aquatic plants are those that are not naturally found in New Hampshire’s lakes, ponds and rivers, and because they are not naturally found here, they have no predators or diseases that keep them in check, allowing them to grow quickly. These exotic plants dominate the shallows of freshwater systems, to the detriment of native plants, fish, aquatic insects and other aquatic life. Exotic aquatic plants lead to water quality impairments, can reduce shorefront property values, and can be problematic to the aesthetic and recreational values of waterbodies.

New Hampshire, with these two new additions, now has a total of 78 infested waterbodies, most containing variable milfoil as the primary invasive plant, while others have fanwort, Eurasian water milfoil, water chestnut and Didymo (also known as rock snot, an invasive algae), among other common species. This tally includes 67 lakes and ponds and 11 river systems.

DES has an Exotic Species Program that focuses on prevention, early detection and rapid response to these plants. Prevention activities are achieved through education and outreach about the problem of invasive species and through smart boater activities that involve inspecting and cleaning transient recreation gear before entering a waterbody and after exiting that waterbody. Boats, trailers, fishing gear, SCUBA gear and other items that come in contact with the water should be checked so that they do not spread exotic plants between waterbodies. Early detection activities are also achieved through a network of volunteers that are trained to identify the various exotic species and to report any new infestations. Rapid response activities initiated at the state level are aimed at containment and control so that new infestations can be eradicated or greatly reduced, so that they do not come to dominate a waterbody.

The two new infestations that were documented were on waterbodies without established programs for prevention and early detection, so they went unnoticed until they covered large areas. When infestations reach this level they are more difficult to manage, and eradication is not often feasible.

The early ice out this year, along with warmer than average temperatures have contributed to more pronounced and rapid growth of exotic species. The DES urges lake and river residents and transient boaters to routinely monitor for exotic aquatic plants and report new infestations. Look for plants that appear to be dominating an area of a lake or river bed, that are brighter green in color, and that appear to be spreading quickly. Maps of existing infestations, as well as information, photographs and descriptions on exotic and prohibited plants in New Hampshire can be found on the Exotic Species Program Page at

For more information or to report a potential new infestation, please contact the Exotic Species Program Coordinator at 603-271-2248.

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NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
(603) 271-3503 | TDD Access: Relay NH 1-800-735-2964 | Hours: M-F, 8am-4pm

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