Ice Safety Tips:
You can't always tell the strength of ice simply by its look, its thickness, the temperature or whether or not it is covered with snow.
Clear ice that has a bluish tint is the strongest. Ice formed by melted and refrozen snow appears milky, and is very porous and weak.
Ice covered by snow always should be presumed unsafe. Ice under the snow will be thinner and weak.
If there is slush on the ice, stay off. Slush ice is only about half as strong as clear ice and indicates the ice is no longer freezing from the bottom.
Be especially cautious in areas where air temperatures have fluctuated. A warm spell may take several days to weaken the ice; however, when temperatures vary widely, causing the ice to thaw during the day and refreeze at night, the result is a weak, "spongy" or honeycombed ice that is unsafe.