A de-icer keeps open water around the dock and the lift. It does not hold the lake level, and it does not replace slack in the cables. Ameren’s December 10, 2024 winter release, as reported by Lake Expo and posted on Ameren’s media site, recommends a de-icer and warns that it “may not provide protection from large ice sheets and blocks.”
This site does not sell units and does not recommend a brand. Prices below are other sellers’ figures, dated, so you can budget a conversation. The install, the aim, and the permit are what a certified dock builder quotes.
How a de-icer works
Agitators (propeller de-icers)
An agitator hangs in the water and pushes warmer bottom water to the surface. Lotolift’s guide puts that water at about 39°F, says a 1/2 to 3/4 horsepower unit can open roughly a 50 to 60 foot hole, and says the unit is less effective at about 6 feet of depth or less. Winter pool on this lake is often that shallow water. Summer pool is not the measurement.
Bubblers (compressed-air systems)
A compressor stays on shore. A perforated line lies on the bottom. Rising bubbles carry water up and hold a ring or a lane open. Lotolift describes bubblers as the shallow-water fit: less electricity, more work to install. No source here gives one watt figure for every compressor. Read the label.
Bubbler vs agitator at a glance
| Agitator | Bubbler | Doing nothing | |
|---|---|---|---|
| Best depth | Loses effect at about 6 feet or less (Lotolift) | Shallow water, including where an agitator fades (Lotolift) | No help when the cove freezes |
| Coverage | About 50–60 feet for a 1/2–3/4 HP unit (Lotolift) | Varies with line layout | None |
| Power draw | Varies by horsepower; use the nameplate | Less electricity than an agitator, per Lotolift; still use the nameplate | None |
| Install effort | Hang from the dock, or a pole or stand mount | Compressor on shore and line on the bottom; more work (Lotolift) | None |
| Unit price reference | Kasco retail, Oct 22, 2026: 1/2 hp $1,016, 3/4 hp $1,110, 1 hp $1,251. Older agitator range $450–$700 | Older bubbler range $585–$755 | No equipment |
| Maintenance | Thermostat or timer; old units can leak oil (Eagle Lake sheet) | Airline and compressor; no single schedule is sourced here | Ice damage is the maintenance |
The older ranges are from a 2016 Eagle Lake association sheet, archived here. They are not 2026 prices. The Kasco figures are one retailer’s shelf on October 22, 2026, at The Dock Box Guy. Shop them. Do not treat them as this site’s offer.
Picking the right one for your dock
Check the depth at winter pool, not summer pool
Measure, or have someone measure, at the end of the dock after the lake has dropped, or estimate from a previous winter. The elevations Ameren publishes are on the lake-level guide. The seasonal order of work is dock winterization. An agitator that worked in August can be in five feet of water in February. That is the depth Lotolift says is a poor match for a propeller unit, and the depth where a bubbler is the tool they describe.
If the dock itself will be on the bottom, fix flotation and cables before you buy a motor to stir mud.
Sizing by horsepower
Use the 50 to 60 foot opening for a 1/2 to 3/4 horsepower agitator as the only coverage number this page will stand behind. A longer dock, or a dock plus a lift, may need a different unit or a second one. Nothing in the sourced material assigns a horsepower by “wood dock” versus “steel dock.” Say which frame you have so the installer is not guessing from a photo taken at noon in July.
Protecting the boat lift
Aim the flow so the open water includes the lift legs and the cradles, not only the swim deck. Ice that locks a cable or a bunk is a lift repair. The lift pages explain placement on the dock. A de-icer does not raise a boat. Take the boat out, or up, as part of winterization, and let the unit protect the hardware that stays in the water.
What de-icers cost
Unit prices
Kasco retail at The Dock Box Guy, retrieved October 22, 2026: 1/2 hp $1,016, 3/4 hp $1,110, 1 hp $1,251, thermostat $150, with a 3-year warranty on those listings. Kasco is here because people search the name. This is not a dealer page, and another brand can be the right machine. The Eagle Lake ranges in the table, bubblers about $585 to $755 and agitators about $450 to $700, are an older sheet. Re-check either number before you buy.
Running cost
Cost ≈ motor watts × hours run × your Ameren Missouri rate.
Lake Hopatcong Foundation and NH LAKES describe thermostats or timers that run these systems about 2 to 4 hours a day. A unit left on from November through March is a different bill. Watts come from the label. The rate comes from your Ameren bill. This page will not invent the product of those two numbers.
Installation
No sourced Lake of the Ozarks installation price was found, so none is printed. Ask for install as its own line on the quote: mount, aim, thermostat or timer, and a spring pull. A winter-watch visit is a second line if you will not be here to see whether the hole is still open.
Wiring rules for a de-icer at the lake
Ameren’s Dock Electrical Installation Requirements, rev. 8.2017, are the constraints on a de-icer circuit:
- GFCI-protected receptacles.
- Receptacles at least 36 inches above the dock surface.
- Weatherproof covers that stay weatherproof while something is plugged in (“in-use” covers).
- Equipment rated for a wet location.
- A shore disconnect within 6 feet of the ramp.
- Bonding of the metal parts Ameren lists, including stiff arms and lifts, to the equipment grounding system.
Adding a circuit or a receptacle is dock electrical work. The fire districts and the Village of Four Seasons require a permit and an inspection. Ameren’s contact list is the map of who inspects. Ameren itself does not. Read the electrical inspection guide and, if that is your shoreline, the Village of Four Seasons page.
Do not run an extension cord down the walkway and call it a de-icer circuit. The rules above are a GFCI, a height, a cover, a wet-location rating, and a disconnect. A cord across a hinge does not meet that list, and it is the first thing the drawdown snags.
Safety and neighbors
Open water and the thin ice at its edge are a hazard for people, pets, and anyone who walks or rides on the ice. NH LAKES tells owners to post thin-ice signage and to aim the unit at their own structure. Aim the plume at your dock and lift. Do not aim it across the cove because the neighbor’s slip looks icy.
The Eagle Lake sheet notes two side effects worth knowing before you buy an agitator. Older units can leak oil. The prop can stir sediment off the bottom, which is more likely when the winter water is shallow. A large opening can also let broken ice floes move instead of staying locked. That is the same limit Ameren states in different words: the hole is not a wall against large ice.
What a de-icer will not stop
Ameren’s sentence is the one to remember: a de-icer may not provide protection from large ice sheets and blocks. If a sheet is going to move, the dock needs hinges that pivot, cables with room to drop, and a person who looks at it. Those steps are winterization and, when the hardware has already failed, cable and stiff-arm repair.
Buying a larger motor does not repeal that sentence. No source used here equates horsepower with protection from a moving sheet.
When to install and when to pull it
Install in October or November, before the first hard freeze, which is Lotolift’s window. A unit bolted on after the cove has already sheeted over is a worse job: colder work, and a dock that has already taken the first ice.
In spring, pull it, clean it, and look at the cord, the mount, and the prop or the airline. Store it where the cord is not crushed. If the thermostat failed, replace that part before next October rather than discovering it on a January night.
A builder’s scope, when you want it done rather than hung by whoever is at the house, is: install, mount and aim, set the thermostat or timer, pull the unit in spring, and include a look during a winter watch if you are away. Say which of those you want. “De-icer” alone does not tell them.
Send the details
Request a de-icer quote. In the notes, include the frame (wood or steel), whether there is a lift, the depth at the end of the dock if you know it, whether power is already on the dock, and whether you want install only or install plus a winter watch. A photo of the slip and of the existing receptacle is more useful than a brand name.
Send the de-icer request. The referral is to one independent Ameren-certified dock builder. We do not install the unit.