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New Hampshire Department of Environmental Services

Media Center

DATE: September 7, 2012
CONTACT: Jim Martin, 603 -271-3710

25 for 25: Keeping Exotic Species Out of New Hampshire's Lakes
By Thomas S. Burack, DES Commissioner

In recognition of the New Hampshire Department of Environmental Services’ 25th Anniversary, over the course of the year, I will highlight 25 agency activities, programs, projects and accomplishments of the past 25 years. This article, the 14th in the series, discusses the impact that non-native invasive species have on our lakes.

In just 25 years, New Hampshire has gone from having a handful of outbreaks of invasive, non-native water plants to nearly 90 known infestations in nearly 70 lakes/ponds and a dozen rivers. In fact, prior to 1965, there were no known exotic aquatic species in the state, but today variable milfoil, fanwort, and water chestnut are just a few of the invasive species that are lowering the quality of New Hampshire’s waters.

Exotic aquatic species are plants or animals that are not native to New Hampshire’s waterbodies. Infestations of these plants can dominate an entire area of a waterbody, often creating a thick band around the shoreline to depths where sunlight no longer penetrates, which results in detrimental effects on the ecological, recreational, aesthetic and economic values of the state’s precious lakes, ponds and rivers, and can decrease shorefront property values by as much as 10-20 percent. Once established, exotic aquatic plant infestations are very difficult and very costly to eradicate.

Exotic plants can grow an inch a day and take over habitat quickly. They can spread from one waterbody to another and even state to state by boating activities, as plant fragments attached to boat motors and trailers can be easily transported. If not properly removed from motors and equipment, these exotic plant fragments can lead to new infestations.

The Exotic Species Program was already an established and active program when DES became a state department in 1987. The importance of this program has only increased over the last 25 years, as DES has worked closely with towns, lake associations and other individuals and organizations to educate boaters on how to stop the spread of these exotic aquatic species.

While the infestations in New Hampshire represent only about 7 to 8 percent of all lakes and ponds, and a couple of hundred river miles, many of these infestations are in prized or high-use waterbodies like Lake Winnipesaukee.

Protection against the further spread of these exotic aquatic plants is challenging, but fortunately DES gets help from hundreds of volunteers through programs such as the Weed Watcher and Lake Host.  These volunteers monitor for new infestations of exotic plants and inspect boats and trailers before they are launched to be sure they are weed free. Both programs help empower the public to be educated and assist in the containment of invasive species.

Today, we are alerted to new infestations earlier than ever, and have developed control actions that are easier to implement and more effective at eradicating these exotic plants.  Just a couple of years ago volunteers detected variable milfoil growing on the northeastern side of Lake Sunapee near Georges Mill. The volunteers reported the growth to DES and the Lake Sunapee Protective Association. DES immediately performed a survey to determine the extent of the infestation, and then worked closely with the LSPA to implement a combination of control techniques, including hand removal and placement of benthic barriers that cover the plants. Thanks to the strong support of the local volunteers, and a couple of follow up visits by specially trained divers, Lake Sunapee is now free of variable milfoil. This scenario is a testament to the effectiveness of our monitoring, early detection and rapid response strategy.

For larger and more expansive infestations, like those in Lake Winnipesaukee and other larger systems, we’ve developed integrated long-term management plans to guide control efforts to a successful outcome. Still, prevention and early detection are our best approaches to this problem. To date, no waterbody that has active Lake Host and Weed Watcher Programs has been added to the list of infested waters, proving that prevention and early detection pay off in both the short and long term.

The DES Exotic Species Program can only be a success with the help and collaboration of all of us who enjoy New Hampshire’s waterbodies. By keeping these undesirable plants out of our waters, we all can all better enjoy our lakes, ponds, rivers and streams, thereby maintaining New Hampshire’s high quality of life.

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NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
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