Dock De-Icers

How to protect your dock and the lake—and stay out of trouble!

Do you use a bubbler, aerator, or similar device to protect your dock during the winter? Are you using it in a lawful and lake-friendly way?!

Find out how to protect your dock and the lake, and follow the law this winter!

Types of De-Icers

Bubblers release tiny air bubbles from a submerged perforated hose powered by an air compressor. They are typically located on a dock or inside a boathouse. Bubbler de-icers don’t stir up lake bottom sediment. They are less likely to cause dangerously thin ice conditions than other devices.

Agitators work by circulating the lake water toward the surface. The entire device is submerged in the water and contains lubricating oil. This oil can leak directly into the water from failed seals. This device needs to be used with a timer and/or thermostat to limit the amount of open water.

Both of these de-icers only need a few hours each day to do their jobs! In addition, a device that runs for only 2 to 4 hours a day will significantly reduce operating costs.

Negative Impacts of De-Icers

There are several potential negative impacts associated with using de-icing devices:

*Opening up too large an area causes dock damage by allowing ice floes more room to accelerate in windy conditions.

*Altering lake water temperature and light conditions may impact algae, cyanobacteria, and plant growth. As a result, this could also impact the feeding habits of fish and other aquatic organisms.

*Disturbing bottom sediments release nutrients such as phosphorus, which will increase algae.

*Creating a safety hazard that can significantly reduce or prohibit winter recreation opportunities.

*De-icers are expensive to buy and operate and do not guarantee less ice damage.

*Circulator de-icers are noisy.

This is an example of a safer and more lake-friendly practice with a de-icer because there is only a small patch of open water around the dock.
This is an example of a safer and more lake-friendly practice with a de-icer because there is only a small patch of open water around the dock.
This is an example of bad practice with a dock de-icer. It has created an excessively large patch of open water which can be dangerous for people and animals that venture onto the ice. The open water area can actually lead to more ice damage to shoreline structures. winter recreationists and this can also lead to greater ice damage.

Tips for safe, effective, and lake-friendly use of dock deicers:

*Choose the smallest possible size to maintain an ice-free zone around your dock.

*Set up your de-icer to form a narrow open water area around your dock (a bubbler device works best for this).

*Point a circulator device in a vertical direction rather than at an angle towards the middle of the lake to minimize dangerously thin ice. Use a purpose-built bracket rather than ropes for more effortless adjustment—most manufacturers offer them as an accessory.

*Use a thermostat or timer to run the de-icer only when the air temperature drops below freezing. (You’ll save a little bit of money, too!)

*Run the device for only 2 to 4 hours a day.

*Better yet, consider eliminating your need for a de-icer altogether! When the time comes to replace your dock, consider installing one that can be removed from the water during winter.

Current State Law for Dock De-Icers

New Hampshire State Law requires all dock de-icers NOT “impede either the ingress or egress to or from the ice from any property other than that of the owner of the device.” This usually means that de-icers need to be controlled, with timers and/or temperature controllers, so as not to prevent access to the lake from neighboring properties.

If you cannot safely access the lake from your property due to the improper operation of your neighbor’s deicer, please share this information with them. They might not know what they are doing is hurting the lake and is against the law. If all else fails, contact NH Marine Patrol at (603) 293-2037 or by email at

When installing a dock de-icer, you must place warning signs so others know their locations. These signs must read DANGER, THIN ICE (like the one shown below) and be of sufficient size to be readable at a distance of not less than 150 feet. They need to be visible from all directions and be equipped with color-coded reflectors in a pattern unique to this purpose.

This information has been adapted from our Lake Sunapee Protective Association partners.

Following these lake-friendly living tips can help protect your dock and the lake, keep others safe, and not get into trouble!

Lake-friendly living is year-round. If you want to learn more about living in a lake-friendly way throughout the season, visit our LakeSmart page!

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