Aquatic Control Successfully Carries Out Three Major Water Chestnut Harvesting Projects

During the summer of 2008, Aquatic Control completed major water chestnut harvesting projects at the Charles and Nashua Rivers in MA and Lake Champlain in VT/NY. Mechanical harvesting is particularly well-suited to provide effective and lasting control of water chestnut because it removes the seeds that the plant uses to propagate. Water chestnut is an annual plant that re-grows from seed each year and with repetitive harvesting (usually 3-5 years consecutively) the “seed bank” can be depleted and the infestation can be significantly reduced and potentially eradicated.

The “Lakes District” of the Charles River is an approximately 200 acre area located in Newton, Waltham and Weston, MA. It is a valuable and widely used resource for boating (especially canoeing and kayaking), fishing and wildlife viewing. Our work on the Charles River actually began in 1995 with an extensive project under contract to the Metropolitan District Commission (MDC) now known as the Department of Conservation and Recreation (DCR) that initially encompassed ~ 80 acres of the Lakes District. During the period of 1995-2001, the annual harvesting program conducted by ACT reduced the infestation to just a few acres of low density water chestnut as a result of harvesting. Unfortunately a lapse in state funding for continuing the project after 2001 allowed the water chestnut to re-grow and surveys conducted in 2007 showed that chestnut re-growth had spread to about 30 acres. DCR selected Aquatic Control to perform the harvesting program in 2007 & 2008. Over 300 hours were put in by three of Aquatic Control’s weed harvesters during each year of the project. Over 450 tons of plant material was removed in 2007, which decreased slightly to 420 tons in 2008. The future of this project is uncertain in the current economy, but DCR and the community are actively trying to find funding for this important project.

Aquatic Control was selected for a similar water chestnut control project by the Nashua River Watershed Association (NRWA) which took place during late July and August of 2008. Approximately 45-acres of the river referred to as the “Pepperell Pond Impoundment” were harvested between July 22nd and August 29th with three large mechanical weed harvesters operating most of the time. Over 1,200 tons of plant material was removed from the river during the first year of this project.

In addition to these large-scale projects in Massachusetts, Aquatic Control has been performing the annual water chestnut harvesting project at South Lake Champlain from just after the Fourth of July to roughly the end of August. The project is directed and funded by the Vermont Department of Environmental Conservation. It also receives additional funding assistance from the US Army Corps of Engineers because it is a navigable waterway. As a result of this ongoing harvesting program, the water chestnut infestation has been greatly reduced as compared to its former range and cover.

The Battle Against Hydrilla Has Moved to the Northeast

Hydrilla (Hydrilla verticillata) is a highly invasive aquatic plant in southern states, but it has been steadily working its way north up the eastern seaboard. The first occurrence in New England was identified in a coastal pond in Connecticut nearly two decades ago. Since then, Hydrilla has been indentified in several more locations in CT, three locations in MA, one location in Maine and at three locations in New York. Hydrilla has been referred to as the “perfect aquatic weed” because of its aggressive growth patterns and adaptive capabilities over a broad range of environmental conditions, allowing it to quickly take over aquatic environments and outcompete beneficial native species.

The most effective strategy to try and halt further geographic expansion of Hydrilla in the northeast continues to be PREVENTION. As with most invasive plant species, once they are introduced to a waterbody, permanent eradication will be very difficult to achieve. Aggressive measures to keep Hydrilla and other invasive plants out of your pond or lake are key and include education efforts, installing signs at access points and proper boat/trailer cleaning and monitoring. Efforts at the state and federal level to prevent the import of non-native plants like Hydrilla have been enacted and continue to be strengthened. It’s important for pond and lake residents to be on the look-out for Hydrilla and be familiar with its characteristics for identification. A fact sheet is available from the Massachusetts Department of Conservation and Recreation that can help you identify Hydrilla. Find it here. There is also an excellent video that can aid in identification produced by the Center for Aquatic and Invasive Plants.

Unless you’re fortunate enough to catch the plant upon introduction, once Hydrilla becomes established in a pond or lake, rapid and aggressive herbicide treatment is typically the only effective management strategy. To date, the herbicide of choice for control of Hydrilla is Fluridone (Sonar). Fluridone will provide systemic (root-killing) control that the “contact” herbicides/products will not. Due to the reproductive structures (tubers) of Hydrilla, multiple years of treatment will be required in pursuit of its eradication.

Aquatic Control, in cooperation with the respective state and local agencies, is now managing all of the known Hydrilla sites in Massachusetts and Maine and we have worked on several of the Hydrilla infestations in CT. Long Pond in Barnstable was the first confirmed occurrence of Hydrilla in Massachusetts in the fall of 2001. Beginning in the spring of 2002, Aquatic Control initiated a Sonar treatment program under contract to the MA Department of Conservation and Recreation (MA DCR) and the Town of Barnstable. Recently we were selected by MA DCR to initiate a rapid response management program at the most recent Hydrilla discovery in Hobomock Pond in Pembroke, MA. This management program will commence shortly and includes treatment of the pond with Sonar herbicide along with reconnaissance and aquatic plant surveys of other nearby waterbodies to search for Hydrilla.

In addition to managing existing infestations, there are continued efforts to study the physiological characteristics of Hydrilla, how it spreads and alternative methods of control. Genetic research is also underway to track different geographic populations of Hydrilla to determine if these populations are linked, which may provide clues as to how they are being spread.

Hydro-Rake Restores Open Water
in Snider Pond - Lincoln, MA

Snider Pond is a 5-acre waterbody located in Lincoln, MA that provides valuable habitat for a variety of wildlife. The pond’s shallow open water habitat had been steadily shrinking due to an expansion of buttonbush (Cephanlanthus occidentalis), in part because of a long period of low-water when the outlet structure was in disrepair.

The Town of Lincoln’s Conservation Commission hired Aquatic Control in 2003 to restore open water habitat to the pond by conducting a Hydro-Raking project to remove approximately one acre of buttonbush, to expand the limited amount of open-water in the center of the pond and create access lanes to numerous locations on shore, including the outlet.

Shoreline access to the pond was limited. After the Town prepared a shoreline location for equipment launching and off-loading of raked material, the Hydro-Rake created a path to the middle of the pond. Material offloaded on shore was hauled to a temporary stockpiling area, where it was allowed de-water before being trucked to a permanent upland disposal site. Over 450 cubic yards of plant and root material were removed during the project.

The Hydro-Rake is a very versatile tool for both small ponds and large lakes and is able to meet a variety of project goals from vegetation removal to debris management and removal of leaf litter and other accumulated bottom debris. GPS was used by Aquatic Control to provide a map of the final raked area to the Conservation Commission, which was very pleased with the success of this project. Even now, some six years post-raking, the majority of open water that was restored, still remains.