by Rainer Park and Pablo Carbonell ·
Friday, June 19, 2026
If you’ve spent time at Bare Hill Pond this spring, you’ve seen it: The water is well below its summer high level. Docks stand high, the shoreline is wider than usual, and boats are harder to launch. Many of you have asked us why—and whether it has something to do with how the pond is managed. Here’s what’s going on, in plain terms.
First, what “full” means. The pond is “full” when the water rises to the top of the boards in the dam and spills into the wetland below. That spillover point is the high-water mark you’re used to seeing along the shore in summer—water up to the banks, good for boating, paddling, and swimming. Right now the pond is about 16 inches below that.
Around 1900, a dam was built that raised Bare Hill Pond above its natural level. Ever since, the town has pulled the boards out of the dam each fall—lowering the pond about 3 feet—and put them back in the spring. This is called a “drawdown.” At first the reason was flood control: A lower pond in late winter could absorb the snowmelt and heavy spring rains that would otherwise flood the wetlands downstream. Pulling the boards brings the pond down to roughly its natural level, the way it sat before the dam was built.
Invasive weeds, mainly fanwort and milfoil, choked the pond in the 1970s and again in the 1990s, threatening the pond’s health. The town’s options to deal with the weeds were limited; back in the 1980s, Harvard residents had voted at Town Meeting to ban chemicals in the pond. A mechanical weed harvester was tried instead, but it was expensive and didn’t work. So a deeper drawdown was proposed: Lower the water far enough to expose the shallow parts of the pond, and winter cold freezes and kills the roots of the invasive plants. Native plants aren’t harmed by the freeze. In the end, a deeper drawdown using a pump was approved and put in place, following a plan submitted to the Conservation Commission and the state. It appears this deeper drawdown has also reduced phosphorous content of the pond, which contributed to the reduction in the risk of algal blooms.
The deep drawdown has worked. When the pump broke in the fall of 2023 and again in 2024, the town could only pull the boards for a shallow, 3-foot drawdown—and the weeds came back with a vengeance. This past winter the pump worked, the cold reached the exposed pond bottom, and the weeds appeared to be knocked back. The boards went back into the dam early this year, because the ground froze sooner than usual.
To understand why the pond is low, it helps to picture the ground around it as a sponge. The lower part of that sponge is soaked with groundwater; the upper part may be drier. The top level of the soaked part is called the water table.
Bare Hill Pond is connected to that groundwater—the pond is simply a low spot where the land dips down into the wet part of the sponge. Because water can’t flow uphill, the groundwater can fill the pond only up to the top of water table level, and no higher. At Bare Hill Pond, that level is about 3 feet below high level—roughly the pond’s historical natural resting level, about where it sat before the dam was built. Groundwater can refill the pond up to that line, but it can’t lift the pond the last 3 feet to the top of the boards. That extra lift has to come mostly from rain, runoff, and streams flowing into the pond.
At the same time, the pond is always losing some water. Some evaporates off the surface. And ever since the dam was built, it has been required to let a steady flow—about 1,000 gallons a minute—go out through the dam to keep the downstream wetlands alive. For the pond to rise and stay full, the rain coming in has to outpace this steady loss going out.
This year, the rain just hasn’t come. It was the driest spring in over 40 years—less than half the normal rainfall. The groundwater did its part and brought the pond back to its natural resting level, about 3 feet below high level. But without enough rain, there wasn’t enough extra water to raise the pond the rest of the way to the top and stay ahead of that constant outflow. So the pond filled partway and stalled where we see it now. The good news is that it wouldn’t take much to close the gap: Because rain across the surrounding area drains into the pond, an inch of rain can raise it a few inches. Just a few steady rainfalls would likely bring the pond back to full.
It’s a fair question, and the answer is that the pond would most likely still be low. No matter what we do, groundwater can only refill the pond to about 3 feet below high level—the rest depends on rain. Even in the old days, when the town only pulled the boards and never used a pump, every inch above that line had to come from rain. This year it didn’t come. The pond would most likely be low whether we had done the deep drawdown, the shallow one, or only pulled the boards. What’s missing is rain.
We know the low water is frustrating, and we don’t take that lightly—a healthy, usable pond is exactly what we’re striving to maintain. Rain has never seemed so precious. In the meantime, the committee and a professional biologist are closely monitoring and evaluating the pond and the conditions around it, and we welcome your questions and your thoughts on how best to care for this shared resource. We look forward to keeping the conversation going. If you still have questions, please feel free to reach out to the pond committee, or attend one of our meetings.
Rainer Park and Pablo Carbonell are members of the Bare Hill Pond Watershed Management Committee. The views expressed here are those of the committee.