What causes Cascade Slush?

[IDFisher]

I realize that later in the year when it gets above freezing and the snow starts melting we get a lot of slush but what causes the slush when it's in the single digits and hasn't been above freezing for 2 months?  Is it the water pushing up through holes where people are fishing or something else?

[panfishman13]

ice is porous, that is to say water can pass through ice given enough pressure.

so when you've got 6+inches of snow on top of a frozen lake, the weight of the snow begins to be enough to start forcing water up through the ice itself, which then combines with snow to make slush, which increases the weight on top of the ice, which forces more water up through.

on the plus side, all you need is a good hard freeze to turn all that slush to ice, which makes walking MUCH easier. unfortunately, we don't have much control over that.

[GrimReaper]

One other complicating factor from the snow just isn't the weight of it pushing down on ice sheet forcing water up through holes and cracks but also the incredible insulating ability of deep snow... it acts as a blanket and prevents the water and slush under the snow from freezing.  The last 3 weekend I have been on Cascade it was been anywhere from -8 to -30F each morning, yet the slush  and water remains in several areas.

Compacting of the snow by warmer temps, wind or driving over it with snowmobiles will reduce its insulating ability and allow slush to harden up.

[fishermantim]

Agree...the deeper the snow cover, the colder it has to be  and the longer it has to be that cold for the underlying water to freeze.

What we end up with here in the Northeast is a "ice fishing lasagna"

Ice, layer of slush or water, ice crust, snow

Only way you know about it is when you step on it and go through the crust.
The water/slush layer is usually a few inches thick, less if the snow later is heavy.

The act of walking on it, breaking thru in different areas, allows for the water to soak into the snow and freeze into a white layer on top.

[icefishingbob]

Good info guys, appreciate it!

[badger132]

The key is to think of the ice as a raft- ice density is 92% of water, so it floats about 92 percent submerged. IF nothing is pushing down on it. Add you, your gear, snow machines, and lots of SNOW, and the equilibrium level of the water can be above the top surface of the ice. That is one reason people think slush gets worse throughout the day. Start out, drill some holes, water comes up through the hole and starts spreading out- you will in general find slushy spots around where there has been a lot of fishing. You also find slush around the edges because water can get around the ice and spread out on top there as well.
The snow insulates the slush, and makes it freeze very slowly. When we get a lot of snow every week, it is hard for the slush layer to firm up, and that is for sure what we have this year, and last. 3 years ago, there was clean ice, and creepers were more in use than snowshoes. I remember the ice did a lot of cracking when the sun would hit it- something I don't hear when it is covered with snow.

For more than you ever wanted to know, look at the http://lakeice.squarespace.com/

[PenguinIII]

Good info thanks guys