news from the waterfront by Tim Matson
SMALL PONDS, BIG ADVANTAGES
One of my neighbors built a pond last year, and
the effect on her landscape was spectacular. A nondescript runoff gully turned into a sparkling sheet of water that refects sky and trees, and attracts birds, spring peepers, turtles, and deer. But the most spectacular thing about this pond is its size: no more than 20 feet across, with a price tag under $2000.
The success of this tiny pond, and a few other minis I’ve seen recently, suggest a couple of things.
There’s a trend in small pond building of late, and it’s worth recalling that small ponds have a distinguished lineage dating back to the days before big mixed-use ponds got popular.
What is a Small Pond?
How do you define a small pond? I’m not sure there’s a red line you go over into “big” pond territory. Somewhere under 20’ to 25’ across might work. Or you could define it by machine time or budget. A pond that can be built in a day or two is likely to be a small one. A pond that comes in for a thousand or two seems fit for small. (Budget doesn’t count if you’re building it yourself.)
In discussing small ponds I want to focus on earth
structures, not garden pools with preformed basins
and elaborate filters and re-circulation systems.
That’s an industry unto itself, with plenty of
descriptive materials and product suppliers available.
Skipping large pond design, we pretty much leave behind multi-use pond options like fire protection, large scale irrigation, beaches and piers, and sport fish that live on natural pond food. So long too, hockey games and swimming, although there might be room for figure skating and wading or sauna bathing. And think how easy it is to shovel off a small pond
for figure skating.
Why build a small pond?
My neighbor knew enough from previous pond ownership that she missed water and the critters water attracts. When she spotted a wet area that showed potential, she went for it, small as it was. The prospect of a low budget was equally attractive.
The pond was built in stages. A test hole the first year. The next year it was enlarged to confirm water supply. Then followed basin, dam, and spillway construction, plus trucking the surplus dredged material to a field for spreading. Total, no more than a couple days’ work.
A Pond For The Dogs
Another small pond I worked on recently had a different origin. The owner wanted a place
for his bird dogs to cool off. His first choice was an open field in full sun. The water supply was limited. I told him the pond would likely lose water level in summer, and heat up and develop algae problems without aeration, supplementary water, and water conditioning efforts. It might require electric service. After some scouting around we decided that a shaded site at the field’s edge showed more promise. Better ground water, cooler, and located where it could receive drainage from roof runoff. The pond would look a lot more natural nestled under some trees next to a stone wall than as a hole in the ground in the middle of a 10 acre pasture.
Small ponds can also work as primarily utilitarian
impoundments. Owners of large ponds sometimes find that adding a small silt pool in the feeder stream cuts down on sediment buildup. A small pond might
be dedicated to garden or farm irrigation. Or it might be part of a network of growing pools for various aquatic species, including crayfish, frogs, and minnows or other fish. It might even be a spring pool to pipe to a larger pond.
True, a few tiny ponds don’t make a movement, and also true that most people I work with are oriented toward big ponds from the start. But small ponds have a few big things going for them.
Nuts and Bolts
Even better than being inexpensive, a small pond might be something you can dig yourself. Perhaps you’ve got a backhoe on a tractor, or you can rent a backhoe. Maybe you have a neighbor with a backhoe who could help. Or get out a shovel and work off some calories. Several shovels and you’ve got a family project. And when the time comes for a cleanout, small ponds are easy to pump out and dredge.
Another plus with tiny ponds is no permitting. Wetland regulations often allow ponds less than 3000 square feet, as long as you’re not mucking about in a protected area or stream. Double check with your town zoning and state water resources to be sure. Make sure you’re not digging into
a water or electric line. And keep out of septic runoff fields.
Water requirements for small ponds may be less challenging than larger impoundments. But like all ponds, water levels will depend on several factors: static level ground water, watershed runoff, and soil/ledge permeability. The good news is that even with poor soil, supply, or retention
capabilities, supplementary water may be enough to offset the loss. If your household well has good storage and recharge, you might be able to use it to top off the pond. Roof catchments and foundation drains can be good sources for supplementary water. Watershed runoff might be improved with ditching or drain pipes feeding the pond. There might even be some ground water below the pond to tap and pump back up.
If these sources don’t work out, you can always install a plastic membrane. However, liners often require design features (flat slopes, underdrain, protective layering above and below the liner) that need to be anticipated before construction. But with a small pond that turns out to need a liner, it might not be a big deal to drain the pond and reconstruct it. Or if you’ve build a real clunker, fill it back in, which is not a big task for a small pond. (Come to think of it, better not spread that dredged material until you’re committed to the pond.)
Water inflows and spillways should be designed like
all ponds. Erosion control is a priority. Flood water should be able to discharge without breeching the dam. An attractive natural-stone lined spillway is a recurring feature in small ponds, which can eliminate piping costs.
A word about basin slopes. To get a nice deep pond of 8 ft or more in a small impoundment, side slopes may have to be steep. But if they are too steep the sides could slump. Compaction may help stabilize basin slopes, as long as the soil contains enough clay to hold together. If the water level
drops much in dry weather, exposed sides will be open to erosion. A protective layer of small stone on the sides may be helpful, but be sure slopes aren’t too steep for the stone to hold in place.
Pond Critters Native and Stocked
My friend with the new pond was relieved when
it was finished, because she fretted about harming her frog population each time the backhoe worked. But the frogs came back. Later, knowing that crayfish can control algae and nutrient debris, she caught some in a neighbor’s pond and moved them to her’s. For mosquito control she bought some minnows at the local bait shop and poured them in.
Flashback and Fast Forward
My friend’s new pond population reminded me of the small scale aquaculture craze of the 70s, and the many experimental mini ponds that were built to grow trout, tilapia, waterfowl, and other aquatic species in various mixtures. The Rodale outfit did extensive small pond research in Pennsylvania. And in Vermont, my neighbor Richard Huke was a pioneer of the solar heated and powered “Aquadome,” where he raised tilapia in water filtered naturally by bacteria in a recirculating waterfall. The pond was a small cement tank surrounded by a vegetable garden that supplied greens and tomatoes all winter. It has always puzzled me that such a simple and successful scheme never caught on.
Nevertheless, gardens are now as popular as ever, and foodies make new (and old) cuisine endlessly appetizing. With a good supply of fresh water, watercress can grow well in small impoundments. Add some cage cultured fish, with crayfish outside to clean up the waste. Sounds like the makings of tasty fryup for small ponders.
Originally published in Pond Boss Magazine