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Pond Ice Alert

December 2019

Tis the season for water to freeze and pond owners to protect against ice damage. Ice can create a skating platform for enjoyable activities: hockey, skating, curling, ice fishing. But ice can also jam pond inflows and outflows, causing flooding and erosion damage. A bad ice jam can lead to pond failure. Let’s head off ice problems so they don’t interfere with pond fun. 


Here’s a look at the problems ice can cause, and how to prevent them.


Piped inflows and outflows are vulnerable to ice damage but will often resist freezing problems if flows are continuous. Pond owners with knowledge of winter performance will usually know what pipes are liable to freeze, or not.

  

Pipes installed at frost level or above are more likely to freeze than pipes installed below frost level. Inflow pipes feeding from another pond or water source at water level may be vulnerable to freezing in especially cold weather. Outflow pipes may be liable to freeze, depending on design. 


A standpipe or riser is not likely to freeze at the inlet unless there is a trash guard that can jam up with debris that creates an ice dam.


An overflow pipe or culvert set at pond water level may freeze due to debris causing blockage that becomes an ice dam. Removing trash guards from standpipes or culverts in winter can help prevent blockages that turn into ice dams.


Standpipes may be vulnerable to breakage due to ice movement, at pipe joints, or lifting of the pipe. It’s best to install standpipes close to the shoreline where they are solidly reinforced by backfill, with just a foot or so of pipe exposed to the water/ice.


The discharge end of a pipe spillway is also vulnerable to freezing, though not likely if discharge is continuous. But if the outlet end fills with debris or has an animal guard it may trigger buildup of an ice dam. If the discharge pipe is a culvert vulnerable to ground frost it may freeze anywhere along the pipe and dam up.


Keep an eye on your spillway pipe outlet to make sure it’s not freezing. Blockages should be removed, including debris and ice. Be careful not to damage the pipe when knocking out ice and debris. In extreme situations you may be able enlist the town road crew to use steam to free up the flow.


Natural earthen inflows and spillways are generally less likely than pipes to dam up with ice. But natural inflows and spillways can freeze up enough to cause trouble (erosion, flooding) if the channel is blocked with vegetation or debris that freezes into a dam. Beaver dams in inflows and spillways can also trigger ice problems. Removal of ice blockages may be necessary, and perhaps removal of beaver dams and beavers. Installing beaver baffles ahead of ice season can prevent ice damming and preserve the beavers too.


Ice can present problems besides flooding and erosion. All structures in the pond can be affected by ice. As ice freezes it expands and moves around, and that movement can damage pond structures. Floating rafts, docks, and piers can be shoved around or damaged by ice. Before winter, rafts are often removed from the water to prevent damage to the floats, and docks anchored to shore may be pulled in for the same reason. Not much you can do about permanently installed piers and docks, but modular docks have gained popularity because they can be disassembled and brought on shore for winter to prevent ice damage.


Another ice sensitive feature in many ponds is stonework. As ice expands and moves, adjacent objects move. Thus, ice affects stones in the water and at water’s edge. Over time a stone retaining wall may lose its footing and shape, and gradually collapse into the water. Stone steps, diving stones, or any stone in the water can be affected by ice. Along the pond edge a stone sitting on the shore may lose its foundation and tumble into the water. The best remedy is good construction. Retaining walls should have foundation stones below ice level, and the wall itself lean back from vertical. Accent stones along the edge might want to be placed further back; the same for the base of a diving stone.


It’s possible to read your pond ice for a couple of useful matters. Before the ice is covered with snow, you might notice black spots in the gray ice, or actual open water. These are often signs of springs bubbling up from the pond bed. If you wonder if your pond has springs and where, this may be your answer. These areas may not freeze as thick as the rest of the surface, especially in early winter, and might best be avoided when going out on the ice.


Stay on the right side of the ice.

Read More Pondologies

Topics vary from month to month and provide great information when researching where you want to build a pond, or how to keep it clean.  Other areas of interest are pond use for more than swimming, and how to keep fish happy in your pond.