How to Buy a Used or Unseen Pond

A Covid-19 news story about real estate in rural New England reported that sales to city folks were up dramatically, with buyers snapping up properties sight unseen. Covid flight, I'd call it.

That story got me wondering how many properties include a pond, and if the buyers are asking the right questions about pond conditions to judge its value and possible need for work.

Some time back I wrote a piece called "How to Buy a Used Pond" which appears in Earth Ponds, The Country Pond Maker's Guide to Building, Maintenance, and Restoration.

Many of the suggestions in that chapter can also be applied to buyers of ponds unseen, prompting the right questions to ask long distance, even if it's not possible to check out the pond first-hand.

What follows is Part One of a two-parter of that chapter; the complete version can be found in the Earth Ponds book mentioned above, and offered in the Books section of this website.  

How to Buy a Used Pond, Part One

At first glance buying land with a pond seems like a good way to shortcut the effort and risk involved in building one from scratch. No preliminary siting work, no searching for the right contractor, no hassles over permits or machinery chewing up the yard. Perhaps this explains why a house with a pond often sells faster than a similar one without. A realtor told me, "A lot of people who want ponds just like to make a phone call and write a check." A lot of the same people quickly discover that buying a used pond is like buying a used car: you just bought someone else's troubles, but they're underwater.

Recently, a woman called me to report that her pond had turned into a half-acre of algae muck, and "there's a horrible smell coming out of the water." Her family had moved into an old farmhouse the previous winter. The pond lay a couple hundred feet downhill from the house. As it turned out, the pond was choked with sediment and contaminated by runoff from an ancient septic system. Not only did the basin need dredging, but the septic system had to be relocated and rebuilt. So much for appraising a pond under a couple of feet of snow.

How to evaluate an existing pond? Begin with a walk around the edge, noting the water quality. Is it clear, cloudy, blooming with algae, infested with weeds? Is water flowing out of the pond through an outlet or spillway, or is the water stagnant?

Clear, or even slightly cloudy water, usually indicates good water quality, while the presence of algae and weeds can spell trouble. A continuing flow of water through a pond is a good indicator of healthy oxygen levels and temperature, while stagnant water is liable to threaten fish and hasten eutrophication, the natural aging process of a pond. Of course, water quality will vary with the season, and evidence of algae during hot weather doesn't necessarily mean the pond is terminal. Depending on the nature of the pond, there may be wild areas of cattails and other aquatic vegetation purposely included as protective cover and a food source for wildlife. However, extensive submerged and emergent aquatic vegetation often means the pond should be cleaned out.

One real estate broker with pond properties observed that prospective buyers are usually repelled by algae and weeds. "People see green stuff and they get turned off," she said, "especially people who can't imagine fixing up a small problem." Conceivably a poorly maintained pond might work in a buyer's favor, as leverage to help lower the price. Naturally you'd want to be confident that the pond could be rejuvenated at a reasonable cost. Conversely, the agent said, a good-looking pond clearly enhances property value. "The key word is good-looking."

A pond diagnosis doesn't end with a weed survey. Leakage is often a problem. Water that drops a foot or so below overflow level during the height of summer isn't a sure sign the pond is doomed. But low water during periods of more generous precipitation hints at problems with leakage, inadequate inflow, or both. 

Note whether it is an excavated or embankment pond. An excavated pond, dug into the ground with little or no dam, is less likely to give you trouble with leakage. If the pond has an embankment, check the outside slope to be sure there is no leakage. Check for signs of erosion, particularly around the outflow area. If the pond has a natural overland spillway system, the channel may need work to stabilize erosion. A piped overflow might require stabilization where water exits the outlet pipe. Check piping to be sure there are no leaks around the outside of the pipe, as well as inside, which could indicate faulty piping or leakage through the dam. Older ponds with metal outlets are particularly vulnerable to leakage due to rust.

Sometimes leaks due to porous soil can be remedied by lining the basin with clay. Membrane liners may also be used to overcome leaks. Supplementary water also can be used to make up for losses. It's a rare pond that won't respond to some treatment, although the therapy may cost as much as the original construction. And it's not unheard of for a frustrated owner to order a flawed pond bulldozed into oblivion.

"How to Buy a Used Pond" Part Two will appear in September.