Variable Milfoil

Of the 28 or so aquatic plant species found in the pond, none has been quite the object of so much attention as Variable Milfoil. An exotic species not native to New England, V. Milfoil has been under management by the state DES as well as the Powwow Pond Council since its discovery during an aquatic plant survey contracted by the council in 2007. Given that the pond contains over 75% aquatic plant coverage already, one may ask : why the concern with milfoil?” The answer may be that this plant is more aggressive in growth than the others and considered an exotic species. While it may provide habitat of a sort for some species of fish, it is thought to decrease the overall natural plant diversity in the pond and to be less important to wildlife.

In June of 2007, two areas of milfoil totaling approximately six acres were treated with the herbicide 2-4-D under the auspices of the State of NH DES, who hoped to nip this pioneering infestation in the bud, so to speak.  Surveys in 2008 revealed only isolated growth and fragments of the plant, but in 2010, V. Milfoil showed up scattered in several new locations. A diver was contracted for suction harvesting work, and much milfoil was removed over three diver days, but late that summer the infestation had spread to new locations and it was apparent that this species was indeed more aggressive than many of the so called native weeds.

In 2011, another round of herbicide application, recommended by DES, was undertaken using funds secured by means of town warrant articles along with PPC funds. As of the end of the 2011 growing season, the infestation is looking like it is under control.  Close scrutiny in the coming season and planning for future control funding will be priority projects for the council.

Water Naiad

Another plant species of note in the pond that has grabbed attention for negative reasons is the water Naiad, Najas guadalupensis, as identified for us by the state Limnology Office. Not considered an exotic, this species exhibits many of the characteristics that Variable Milfoil is noted for when it comes to affecting recreational activities and forming mono cultures (large areas of the same species), although it has value to wildlife and fish. Most pond residents don’t remember seeing it prior to about 2005, but during some years it can be observed in large areas of the pond growing to the surface. It is said to resemble a tangled hair net, and makes it virtually impossible to operate a motor boat, swim, or even effectively use a fishing lure in the areas where it is most dense. It is an annual, thus spreading and regrowing by means of seeds, and that probably explains why it has variable growth and density depending on conditions of that particular year, and why it doesn’t appear at the surface until August usually. Its seeds probably  also allow it to spread over the entire pond.

Other Aquatic Vegitation

A diversity of aquatic plants are an integral part of a healthy, thriving lake or pond system. They provide food and cover for wildlife and fish, and oxygenate and filter the water. Aquatic plants thrive in the littoral zone, the area where sunlight can reach the bottom and stimulate plant growth, and most lakes are fringed with plant growth in their littoral zones. In the case of Powwow, the entire pond is a littoral zone, and a fairly shallow one at that, allowing plants to reach the surface easily.  The amount and type of plant coverage as well as the species that are desirable in a water body, seems to be as much a matter of opinion as it is one of scientific certainty. If you are a muskrat trapper or duck hunter, a marsh situation with 90 -95 % plant coverage may be desired. If you are motor boat cruising, swimming, or water tubing, less than 25% may be your preference. Anglers may desire something in between. The Powwow Pond Council has raised the question, given that this pond is artificially dammed, and very shallow, “can we manage the rate of natural plant succession and growth in such a way as to allow the current diverse recreational use that it is receiving, without upsetting the ecosystem and sacrificing fish and wildlife values?”We are certain that we do not want plant succession to continue with the dominant presence of Variable Milfoil in the mix!