Forge Pond Winter Drawdown 2024-2025
The Friends of Forge Pond performed a drawdown of Lake Matawanakee / Forge Pond during the winter of
2024 – 2025. The weather was much more favorable for the drawdown than in the two previous winters. As
shown in the figure below, the longest below-freezing period was just short of 7 days. And there were enough
additional freezing days with low water to produce a moderately effective result.
Winter drawdowns are the most environmentally benign means to control invasive aquatic plants in the lake.
Freezing and drying the exposed lakebed inhibits these plants in an environmentally favorable manner. About
two weeks of hard freeze with low water are needed to accomplish this. The longest continuous period of freeze
with low water during the reporting period was almost a week, and more than an additional week of freezing
days occurred. It would have been better to have the freeze days occur all together, but it appeared there was
enough freeze with low water to be helpful in controlling the plants in the exposed areas.
In the areas not exposed by the drawdown, ice and snow cover during winter also affects the summer density of
invasive plants in the lake. When the lake freezes over and snow falls on the ice, if the snow is thick enough, it
blocks the sunlight from reaching the plants, and they die back. For the previous two drawdowns, the lake froze
only briefly and this did not occur, with the result that each summer’s new crop of plants was added to the
plants still in place from the previous summer. During the most recent drawdown, we had about 3 weeks of ice
with deep snow cover, which was enough to reduce the plant density some, but not a lot.
Results of drawdowns vary from year to year, due to variations in precipitation and temperature. Even with
these variations, a series of annual drawdowns helps decrease invasive plant growth, improving both the
wildlife habitat and the recreational quality of the lake.
The 2024-2025 drawdown began on October 15, 2024. The lake level elevation at the start was just above 204
feet, near its typical late summer level. It was a few inches above the threshold of the main spillway of the dam.
Removing the spillway flashboards, opening the sluice gates and taking out stoplogs lowered the lake over the
next month by almost 4 feet to 200.5 feet. The target level is just below 200 feet.
From late November until March, the lake level fluctuated with the weather, varying between 200.3 and 202
feet. Hard freezes were intermittent, as shown in the figure below, but in aggregate produced a useful result.
The lake iced over early, but the cold didn’t last and it melted. It iced over again in late December, providing
great skating. But snow didn’t seriously block the light to the plants below until mid-February. March was
warmer than normal, melting the ice and the snow. The result was that the period of darkness under the ice
wasn’t long enough to decimate the invasive plants. When the spring came, a large fraction of the previous
summer’s plant population remained in place in areas that were not exposed by the drawdown.
The variations in lake level during the drawdown are shown along with air temperature in the graph below. Data
points are plotted every 15 minutes. The Order of Conditions governing the drawdown allows the level to fall to
199.9 feet, but the lowest level reached was 200.3 feet, and that for just a few days.
Achieving a sustained hard freeze requires repeated night-time temperatures below 20°F. This occurred about a
dozen times on scattered nights throughout the winter. So the objective of exposing the lakebed to a sustained
hard freeze was not achieved. Shaded areas in the graph indicate intervals when the air temperature stayed
below freezing for more than 24 hours.
Warm weather melting and rain began refilling the lake in early March. The Friends of Forge Pond began a
controlled refill of the lake on March 15, 2025. By April 1, 2025, the lake level was about 205 feet, achieving
the level required by the Order of Conditions.
Friends of Forge Pond
