WATER QUALITY PROGRAMS FUNDED BY THE NLWA
The mission of the Northwood Lake Watershed Association, (NLWA) is to preserve, protect, and improve the environmental quality of Northwood Lake.
Voluntary Lake Assessment Program (VLAP)
VLAP was launched in 1985 to establish a citizen-based lake sampling program to assist NHDES in evaluating lake quality throughout the state, and to empower citizens with information about the health of the state’s lakes and ponds. This cooperative effort allows state biologists and lake associations to make educated decisions regarding the future of New Hampshire’s lakes and ponds.
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The NLWA funds collection of water quality samples at the deepest spot of the lake and at the tributaries entering and exiting the lake. These samples are collected several times throughout the summer months.
The Need To Control
Milfoil Control
Variable milfoil is an invasive aquatic plant. Left untreated, these plants can cause catastrophic damage to the health of the lake. The damage has huge impact on property values and the local economy.
Once established, Variable Milfoil can out-compete native vegetation. Species that depend on that native vegetation to survive are forced to relocate or perish,
resulting in a loss of biodiversity. Variable Milfoil produces dense large mats of vegetation on the water surface, thus intercepting sunlight leading to the exclusion of other submerged plants.
​Variable Milfoil greatly impedes boaters, fisherman, water skiers and swimmers, and these limitations on water use can negatively impact real estate values.
When dense mats of Variable Milfoil decay, the available oxygen in the water is depleted. The resulting low oxygen conditions (anoxia) can lead to fish kills and harm other aquatic organisms.
What is Milfoil?
Variable Milfoil is an aquatic rooted, submerged non-native plant with a “raccoon-tail” or pipe cleaner appearance.
Variable Milfoil can form dense mats at the water surface and can grow in the photic zone, in up to 10 feet of water.
The delicate green underwater leaves are feather-like and average 1⁄2 to 2 inches across. Leaves are arranged around the stem in whorls of 4-6. The leaves have 6-12 segments.
During late summer a 4-6 inch emergent bract develops, protruding above the water surface. The small bright green leaves on the bract are oval and are both serrated and non-serrated. (The lower female section of the bract has serrated leaves, and the upper male portion has smooth margins).
The stems are thick, robust and usually red.
Managing Milfoil On Northwood Lake
One of the founding reasons for the Northwood Lake Watershed Association was to control invasive milfoil and other organisms that harm the lake. Thanks to the efforts of the NLWA Milfoil contamination has been largely reduced in recent years.
Control Methods
Diver Assisted Suction Harvesting
(DASH)
Diver Assisted Suction Harvesting (DASH) is the extraction of plants using a diver, suction tube, a unique set of pumps mounted on a boat and a bagging or filtration system. Suction harvesting is a viable means of plant suppression because the entire plant is removed in its connective rooting system.
Chemical Treatment
In 2021 Solitude Lake Management Chemically treated sections of the lake with
liquid PROCELLACOR EC tm(Florpyrauxifen-benzyl) herbicide treatment to control
invasive variable milfoil in the lake (treating 57.1 of the 686 acres).
Manual Hand Pulling
During hand pulling, milfoil plants are manually removed from the lake bottom, with care taken to remove the entire root crown and to not create fragments. Due to expense and the time intensive nature of manual methods, sites suitable for hand pulling and bottom screening are limited to lakes or ponds only lightly infested with milfoil. This method is suitable for very early infestations of milfoil and for follow-up removal after a large scale control project.
Lake Hosts
The NH LAKES Lake Host Program is the first line of defense in protecting our lakes from invasive plants and animals. The NLWA participates in the Lake Host Program inspecting boats coming in and out of the public landing.
Lake Hosts conduct courtesy boat and trailer inspections of vessels both entering and leaving public waters and show boaters where to look for hitch-hiking plant fragments on boats and trailers.
They offer free complimentary boat inspections to teach boaters about the Clean, Drain, and Dry method for aquatic invasive species prevention.