Fishing · Full day · Advanced
Ice Fishing: Thickness Numbers and Carbon Monoxide
Two things kill ice anglers: thin ice and a fuel heater in a closed shelter. Minnesota DNR's thickness guidelines and ventilation rule, with the caveats attached.
This is for educational purposes only. Not professional medical, electrical, or safety advice.
Warning
Under 4 inches of new, solid, clear ice, stay off, and double that guideline for white ice — but no thickness number guarantees safety. A fuel-burning ice shelter needs ventilation and a working carbon monoxide detector.
- 01
Read the numbers as they were written
Minnesota DNR's ice thickness guidelines apply to new, solid, clear ice only: under 4 inches, stay off; 4 inches is the guideline for foot travel and ice fishing. White ice is about half as strong as clear ice, so double the thickness guideline where you have it.
- 02
Treat the number as a floor, not a promise
These guidelines are not guarantees. Ice strength can change dramatically within a few yards, and currents, springs, snow cover and thawing all change it. Check thickness as you travel rather than once at the shore, and do not treat another angler's tracks as proof.
- 03
Fish the hole you can justify
A source-supported tactic is bait fishing through a safely established hole for panfish using minnows or waxworms, subject to current tackle and bait rules. There is no official basis for improvising access across thin ice, crossing river ice, or cutting a hole without safe equipment.
- 04
Ventilate before you light the heater
Minnesota DNR's guidance for propane-heated ice shelters is ventilation plus a working carbon monoxide detector, with an incoming-air opening within 1 foot of the ground plus an upper opening, and vents kept clear of snow. A heater's low-oxygen shutoff is not a substitute for a carbon monoxide detector.
- 05
Never trust one measurement
A single reading at the entry point says nothing about the middle of the lake. Re-measure along your route, and turn back when you find the thickness dropping rather than hoping it recovers.