A Pond in the Woods
By Tim Matson
(originally appeared in Northern Woodlands Magazine, Summer 2007)
All ponds have water in common. It’s their surroundings that tell them apart. The pasture pond is a sun-splashed delight prized for its recreational opportunities and as a landscape accent. The shadowy woods pond, on the other hand, evokes instead a mysterious realm of covert creatures, hidden wildflowers and plants, and rich ecological complexity. Unlike the vacationer’s sandy beach, the wooded pond belongs to the poet and the naturalist. Creating it may require an afternoon with a tractor or a backhoe – or months of permitting, terrain testing, pumping and dredging, and a bushwhacker’s determination. But come easy or hard, the wooded pond can yield the richest of pond pleasures.
It’s not necessary to build a pond deep in the boreal backwoods to reap the rewards of the forest neighborhood. Many ponds are bordered by woodland features, and there is one significant advantage to siting a pond near mature woods: instant naturalized landscaping. Other incentives to building in a wooded site may include a good water supply, water-retaining soils, and the natural privacy and sound buffer provided by trees.
Naturally protected wooded ponds are often superior to exposed sites for creating wildlife and waterfowl refuges, and for the same reason, make good constructed wetlands. Animals like their privacy, too. Removed a bit from human activity, woods ponds often feature duck boxes hung on shoreline trees, which can provide nesting for wood ducks, mergansers, and other water cavity nesters. Floating wooden platforms or constructed islands can also provide safe nesting and cover for waterfowl.
Like a natural beaver pond, a wooded pond is a magnet for wildlife. The water attracts a whole different set of songbirds than those in the unbroken forest. Mink, otters, and herons will find their way to a pond that holds fish and crayfish. Deer and moose are drawn to water, and whether you like them or not – and many pond builders do – beavers may take up residence in a wooded pond.
Finally, consider the pleasures of presiding over your own private Walden. Easily the most famous wooded pond in America, this kettle pond was such potent inspiration to Henry David Thoreau that his Walden became an American classic.Writing a masterpiece must be hard enough, so it’s a good thing that Thoreau didn’t have to build his pond to boot. Pond building is tricky, and plunking down a pond in the middle of the woods can sometimes be a real bear.
In the first place, it can be difficult to envision and map a pond perimeter when the terrain is covered with trees. And if a pond is to be built, trees must be cut, stumped, and removed – but how far do you need to go? Some constructed shoreland around the pond is usually necessary, but how much? Just enough to stabilize the shore? Enough to admit warming and photosynthesizing sunlight? Enough to create terrain that can be used for work, play, or camping? Which perimeter trees should be preserved? Which are at risk of dying due to elevated water levels or a sudden increase in the amount of sunlight? If a dam is required, the woods will have to be cleared for a foundation that is roughly three times wider at the base than the dam’s top. These are all questions the woods pond builder should consider before exchanging forest for water.
Then there’s the classic woods pond Catch-22: you don’t want to build the pond until you know the site is suitable; the only way to tell if the site is suitable is to build the pond. It may be difficult to determine the site’s feasibility without clearing significant areas for soil, water, and ledge test pits. And if the tests are negative, or suggest pond costs beyond budget, you could be left with a dish of chopped forest and no pond.
Keep in mind that woods are woods often for a good reason. The terrain may not have been suited for pasture or meadow because of rocks or ledge. In other words, crummy plowing and digging. I worked with one landowner recently who had several acres of attractive softwood forest clearcut for a pond, but when excavation began, the ground revealed a forbidding layer of granite ledge. The contractor prescribed black powder, so the basin was blasted, and in the fall a large embankment went up. The pond filled beautifully the following spring but soon began showing signs of serious leaks. It turned out the ledge had been so badly fractured that despite a large inflow from streams and runoff, the pond wouldn’t hold water. After many fruitless and expensive attempts at patching, including clay liners and embankment repairs, the pond had to be refilled with earth. There’s an apple orchard planted there now, something of a pond memorial.
The best way to avoid expensive repairs (or worse) is to select your contractor carefully and check references, including customer recommendations and site visits to confirm his expertise (and perhaps pick up design ideas). It’s better to pay more to get it right the first time with a reputable contractor than to cut corners using a neophyte and build the pond twice.
I’m often asked to estimate pond costs, a question even contractors prefer to finesse. It’s not like estimating a new house. The variables are huge and often change during construction: pond size and shape, piping options and costs, engineering costs, need for supplemental water, liners, contractor rates, and of course, the weather, which can raise the price if it works against you. Most contractors work on a time and materials basis, after beginning with a rough number in mind, and bearing in mind that spontaneous changes in customer design can alter price variations. Okay, you want that rough number? From the simplest swimming hole or quickie wetland to a small loch: say somewhere between $5,000 and $100,000.
Besides paying for the pond, other challenges associated with wooded impoundments include hardwood leaf litter in the pond that can lead to water quality problems, water discoloration due to leachate from runoff areas draining through softwoods, and lack of sunlight, which can adversely affect water quality. No photosynthesis equals no oxygen equals eutrophic H2O. In layman’s language, swamp water. That might be fine for a constructed wetland, but not so good for swimming.
However, there are solutions. Litter can be periodically removed by hand, after dewatering and dredging the pond.Native crayfish can be stocked for their natural capacity to devour pond bed detritus. And spillways and inflow/outflow currents can be designed to naturally flush out leaves and debris. Wind flow patterns should also be analyzed during spillway design to see if the prevailing winds can be utilized to help blow leaf litter and floating debris out of the pond.
The clearing surrounding a woods pond will likely be the site of active natural tree seeding. This requires maintenance to prevent saplings from rooting,which could become invasive in the water, or jeopardize a dam or shore structure, leading to leakage or erosion.
Because trees absorb a lot of moisture during the warm growing season (when vulnerable ponds tend to go dry anyway), summer runoff to a woods pond may be reduced, leading to low water and consequent water quality and aesthetic problems. Supplemental water may be required to maintain good water TIM MATSON quality and an attractive pond with a consistent waterline.
There may also be legal issues connected to woods pond construction. If the site includes wetlands that fall under state or federal wetland jurisdiction, permitting may be required. This could require surveying or engineering costs that may or may not lead to a green light for pond construction.Aspects of concern to wetlands agencies include erosion control, stream alteration, stump removal, and direct disturbance of a protected wetland or effects on a contiguous wetland. Besides, who in good conscience would destroy a wetland or vernal pool to replace it with a recreational pond of less complex natural value?
In addition to legal constraints against wetland pond construction, there’s another caution worth considering. Wetlands often harbor beavers, and beavers love to mess around with ponds. If you sink a pond in an extensive wetland area, you may find yourself in a tug of war with a family of beavers who would like nothing better than to plug up your spillway. Pond failure and damage downstream are often the result. It is true that some people design ponds intentionally to attract beavers, but these ponds often require specially designed spillways to prevent flooding.And bacteria and parasite contamination often rule out swimming.
Various states and municipalities may have regulations regarding pond construction, and it is the landowner’s responsibility to comply with these laws. For example,Vermont has a new general construction law requiring a permit for any construction affecting one or more acres.
If your wooded pond site is enrolled in a state current use program or other management program, be sure to consult your state tax department or forester about the legality of adding a pond. Maine allows redesignation of current use land so that a recreational pond built in a “Tree Growth” area can be newly permitted as “open space.” In Vermont, however, building a deep-water recreational pond in woodlands enrolled in Use Value Appraisal requires withdrawal of the pond’s acreage from the program; on the other hand, building a small, shallow-water pond for wildlife habitat is permitted.
If building a pond in the woods, rather than in a clear meadow, presents so many challenges, why bother? It may be that the only land you have available for a pond is in the woods or simply that you would prefer a pond in the woods. Think Thoreau. Trees create excellent visual and sound buffers, and thus a woods pond can offer valuable privacy.
It could be the only place, or it could be the perfect place. Perhaps the woods site is where the best pond water supply occurs: an on-site spring; a runoff gathering area; the receiving end of a small stream or piped spring; or a spot to maximize collection of runoff using swale, ditch, or buried perforated pipe (French tile).
Piping in water from a stream often involves installing a cistern at the edge of the stream, uphill from the pond.Water collects in the cistern and flows by gravity to the pond. The pipe is often buried below frost level to prevent freezing and pipe damage. Depending on stream volume and wetland classification, you may need to obtain permits for stream alteration and water diversion.
As for soil, your test pits will show if you have good waterretaining soil (having at least 10 to 20 percent clay),which adds to the odds for success, unless you plan on using an artificial liner.
In rural areas, most folks building earth ponds like them big enough for swimming, skating, and perhaps raising fish, with many other potential uses including fire protection, farm and garden irrigation, hydropower, and more. These ponds usually range in surface area from 1/8-acre to one acre and are generally about 8 to 14 feet deep. They are recreational ponds, but they also provide habitat for wildlife.And when they are located in the woods, removed a bit from human activity, animals and birds are even more likely to use them.
On the other hand, some pond designers use the woods environment to create much shallower ponds, also known as constructed wetlands. Constructed wetland ponds are usually shallow, perhaps a foot or two deep, and are often allowed to grow whatever native aquatic plants happen to naturalize there. If you’re bringing in aquatic plants, it’s important to limit them to species native to your region. These wetlands support all sorts of birds, mammals, and aquatic animals. Like natural wetlands, they help to filter and clarify watershed runoff and, by sponging up water, reduce flooding.
Whether you dig a wetland or recreational pond, the wooded environment offers a rich palette for the creative pond builder, as well as a shady spot to leaf through Walden – or to write your own masterpiece.