LETTER: Future Water Quality of Groton's Largest Lake by Alex Woodle
Groton Lakes Association (GLA) is asking for $95,000 to treat Lost Lake/Knops Pond with an herbicide as the first part of a comprehensive Resource Management Plan (RMP) to restore and maintain the quality of this 204-acre natural resource. The threat to the health, safety and recreational value of the lake is very real. Without immediate intervention the water quality in Lost Lake/Knops Pond, which already is severely impacted, will also negatively affect property values and tax revenues.
Twenty years of implementing various methods of weed control have met with limited success. The new approach is designed to eliminate non-native weeds from the lake and prevent their re-infestation. Selectmen, Conservation Commission, Board of Health, Water Commission, Planning Board and Finance Committee have all voted to support this program.
The herbicide Sonar, successfully used throughout Eastern Massachusetts, with proven safety in primary water resources, has been selected. The only restriction in its use is irrigation. The second part of the RMP is to conduct a thorough inventory of the erosion and storm water run-off within the entire watershed, encompassing approximately 2800 acres. GLA is working closely with the Groton's Earth Removal and Stormwater Advisory Committee and Conservation Commission to begin this assessment. The third piece of the plan will involve introducing a boat inspection program at the public access point to prevent non-native weeds from being re-introduced into the lake. Finally, GLA will be proactive in developing and distributing educational materials for the maintenance of lakeshore property, employing inexpensive, effective ways to minimize nutrients loading into the lake.
Physical and Cultural History of Knops Pond/Lost Lake
During the last ice age Groton was covered by a massive continental ice sheet measuring more than a mile thick. Its advance and decline some 12,000 years ago shaped the current land surface today.
Many glaciated features remain, including drumlins Gibbet Hill and its neighbors, Chestnut Hills and Indian Hills, all shaped by the ice sheet. Another glacial feature is the esker, long winding ridges that represent a three-dimensional cast of glacial streams flowing within the ice sheet. Many Groton's roads are located atop these ridges. Examples include Ridgewood, Whiley and Boathouse that surround Lost Lake and Knops Pond.
A third common landform left by the ice age is the kettle pond. Walden and Jamaica Pond are two well-known examples. In Groton we have several, including Knops, Whitney, Baddacook and Martins Pond. They were formed by blocks of ice breaking off the melting ice sheet, becoming buried in sediment flowing off receding ice. When the ice blocks fully melted, they left depressions. This was how Groton's ponds were formed.
In Colonial times a few brave people lived by these ponds. Several years ago a resident on Knops Pond was diving and found a colonial kettle as evidence of early settlement. One of the first settlers in Groton was James Knap or Knop for whom Knops Pond was named.
An adjacent kettle, called Springy Pond, joined Knops Pond around the mid-nineteenth century when a dam was constructed, allowing the water level to rise. Harbor Mills of New Hampshire secured water rights (1860s) and installed a wooden dam. The rising water level served the needs of an ice harvesting operation located below Ridgewood Road. The original remains of the icehouse and haulage road can still be seen. Harvesting of ice on New England ponds was a major industry prior to refrigeration.
Around the turn of the twentieth century a second dam was constructed downstream from Knops Pond, inundating the adjacent Cow Pond Meadow, later named Lost Lake. This was one of several dams built along a 15-mile watercourse guaranteeing a consistent flow to power a mill in Nashua.
During the 1920s Lost Lake Development was formed to take advantage of the growing leisure requirements of city people seeking to build summer cottages on lakes that had become more accessible with improvement in transportation. Lost Lake/Knops Pond became a favorite summer resort for people looking to escape the hot city.
Lost Lake Development and the bank which financed it declared bankruptcy within a short time. Economic circumstances forced many residents to convert their summer camps into year-round residences. In the 1970s conversions picked up again. Today most lakeside dwellings are year round.
Sometime in the 1960s a now defunct sportsmen's club purchased some waterfront land at the northern end of Lost Lake to operate a boat launch. This boat launch is now owned by the state. Fishing has always been popular and the state has stocked trout in Knops Pond every spring. Recreational activities on Lost Lake/Knops Pond reach their peak between Memorial Day and Labor Day with swimming, boating, water skiing, tubing, fishing, kayaking, canoeing and some sailing. Most lakeshore residents have their own waterfront docks for boats and swimming. Grotonwood camp maintains a large beach for their campers. Mountain Lakes Club provides bathing at Baby Beach.
Groton owns a 19-acre woodlands and waterfront area known as Sargisson Beach. For many years this maintained beach offered swim lessons to Groton residents. A few years ago the town defunded the Recreation Department and stripped Sargisson Beach from the budget. The area no longer has lifeguards or docks for swimmers. A resurgence of interest in 2012 has begun to take hold and residents are developing a groundswell of support for the beach to be re-opened and staffed once again. This past summer two beach clean-ups were accomplished by volunteers. This fall an Eagle Scout project for stormwater run-off and erosion was begun. This on-going project will be completed in 2013.
The Conservation Commission, Groton Lakes Association (GLA) and Earth Removal and Stormwater Advisory Committee have begun working together to seek funds for a stormwater study of the Lost Lake/Knops Pond Watershed that encompasses approximately 2800 acres. This is one of the major goals of the Resource Management Plan developed by the Groton Lakes Association. The other major goal this coming spring is treating the whole lake for non-native invasive weeds that have clogged most waterfront properties and threaten the overall health of the lakes.
Efforts to reduce or Eliminate Non-Native Weed Infestation
Long-term lake residents in the 1970s and 1980s noticed a steady increase in weed growth. Clean Lakes Committee, an early version of GLA, was formed. A contractor was hired to hydro-rake the weeds. The following year the infestation was worse. Subsequently an environmental firm, Baystate Environmental Consultants, was hired to conduct a comprehensive survey of the lake and its surrounding watershed.
The Baystate study recommended alternatives to try to manage the growing infestation. The most economical and environmentally sound option was to do a winter drawdown significantly lower than usual to expose the weeds to frost. Once the weeds were frozen, the water level would be raised so that the weeds would be ripped from the lake bottom. This strategy ultimately failed. State restrictions and shallow wells precluded draining Lost Lake and a significant portion of Knops Pond which would have been necessary to expose and eliminate the invasive weeds.
Dredging was a suggested solution, but the cost would run into tens of millions of dollars, require numerous permits and years to secure. Other ponds that have tried dredging have seen a return of invasive weeds.
Hand pulling an invasive weed called fanwort was attempted at the boat launch where it was believed to have first entered the lake. This was very difficult because of the mucky bottom. Visibility was immediately impaired, obscuring removal operations.
A mechanical harvester purchased by GLA in the 1990s to try to keep waterways open by cutting and removing the weed called milfoil became a means to an end. Unfortunately, while this technique keeps waterways open, not all cuttings can be collected. As a consequence, these cuttings root themselves and become new plants thereby spreading the non-native weeds.
In 2002 permission was secured to use an herbicide to treat for milfoil and the harvester was retired. This treatment was very successful. Spot treatments in 2003 and 2004 were used to eliminate some areas of regrowth. This program was shut down by the state when it was alleged that an endangered Massachusetts aquatic plant was inadvertently and adversely affected by this application.
Bottom covering materials called benthic barriers was tried in Knops Pond in late 2004. They are expensive (about $1.50 per square foot), difficult to install, require frequent maintenance and are almost impossible to remove. By the time permission was secured from the state to use them in two small areas, infestation had spread throughout the lakes.
Following this effort, the state allowed only mechanical harvesting to control weeds. The weed harvester, owned and operated by Groton Lakes Association, tried to keep up with new growth. Harvesting became the only means to help keep the waterways open and beaches and waterfronts clear, but the weed infestation worsened.
The mild 2011-12 winter did not allow the usual winterkill of weeds to occur. As a consequence, summer 2012 saw the worst infestation in history. Most shallow areas of Lost Lake and Knops Pond were completely infested with milfoil and fanwort. Shoreline residents were severely impacted by this infestation and swimming from their docks was virtually impossible. Limitations of the harvester, combined with the warmer winter, created an explosion of weed growth.
Future Outlook for Resource Management of Lost Lake/ Knops Pond
During the past year GLA has developed a resource management plan and heightened awareness in the community and its various boards to the growing problems for the lakes. The threat to water safety, boating and fishing; the problem of stormwater erosion entering the lakes; lack of control at public boat launch; and continuing nutrient loading from septic systems and poor land use practices are the main obstacles to restoring Lost Lake/Knops Pond.
The first step in restoring our lakes is for a whole lake treatment in spring 2013 with an herbicide called Sonar. It interrupts plants' ability to photosynthesize and is very effective on the two main invasive weeds, milfoil and fanwort. This herbicide has been used successfully in public water resources throughout Massachusetts (27 ponds in 23 towns in eastern Massachusetts), including Spectacle Pond, a primary drinking water supply for Littleton, Flanagan's Pond and Sandy Pond in Ayer.
The treatment in spring when the level is at its lowest will attack new weed growth before they can dominate the water column. Lack of plant biomass will lower the risk of an algae bloom and not impact summer activities at the lake.
GLA together with the Conservation Commission and Earth Removal and Stormwater Advisory Committee will be seeking funding for a stormwater management project for the watershed.
GLA will be working closely with the town, state and Conservation Trust to access a control plan and boat inspection station at the public boat launch. These will prevent the re-introduction of invasive weeds and arrest their export to other lakes.
Finally, GLA will launch several programs to educate lakeshore residents on use of phosphates, maintenance of septic systems and land use practices on their waterfront property to reduce and/or eliminate stormwater run-off and erosion.
The state will offer a weed identification program for residents. GLA will create a rapid response team to any reported re-infestation. In addition a water quality program will be instituted to take samples in all Groton's ponds to monitor their health.
Groton Lakes Association and Knops Pond/Lost Lake residents plan to work closely with town boards and interested members of the community to restore and maintain the beautiful Sargisson Beach area for all Groton residents.
Special Town Meeting Saturday, January 26, at 9 a.m. will have an article in the town warrant to fund treatment of Knops Pond/Lost Lake. We hope all of you will turn out and support this article to preserve and protect one of Groton's finest natural resources.
20 Highland Road