Lake hazard?

I remember crossing one of the Chain Lakes - the one west of Herman Saddle about 20 years ago on a cold mid-January day. I recall that it had been cold for several weeks. As I moved onto the lake snow depths looked to be three feet over the lake, but near the middle of the lake a pole thrust showed 10cm of marginally frozen surface and black water beneath. It scared the you know what out of me as I gently double poled off the lake surface. I came to the conclusion that geothermal activity may have had something to do with it. Otherwise it just didn't make sense.

By coincidence, it was in crossing the Chain Lakes that we were concerned. All the lakes had visible water at one or more inlet/outlet points and we did not know if that was a bad sign or a normal occurrence. So we went around them especially the highest one which is pretty large.

Ok Gary that is a spooky story. Were there any telltale signs at all in the snowcover?
Going under water with a heavy pack and locked dynafit toepieces is not on my agenda but skiing across frozen lakes is one of my favorite parts of winter.

I would like to respond to Gary's post. I haven't had time to read all the posts, so this point may have been made already.

Even on a well frozen lake, the addition of lots of snow on top can weight the ice in such a way that water can flow over the top of the ice and into the lower layers of the snow. Also, here in the PNW, a deep snowpack on a lake is going to act to insulate the lake and reduce exposure of the water surface to either cold air or radiational cooling that really can deepen the ice. There is a huge reserve of latent heat in any body of water, even water that is near 0C, so snow insulation will mean that essentially very little more ice thickening will occur.

I have found that it is not uncommon to ski across lakes in the PNW (have done so near Stevens and up in southern B.C.) in late winter/early spring and notice water wicking up into ski tracks. This is usually from that water that has overrun the ice below.

However, no matter what the reason, it is still spooky and you can't always tell how secure you are on the surface. The other thing that I can imagine happening is that the overrunning water could erode the ice underneath the deep snowpack by driving the ice into the warmer water below. Not sure how plausible that is, but the prospects are still scary.

Alan

If you start skiing across and it turns out to be a bad idea, do you get any feedback before catastrophe strikes?

Good question!  I had occasion to ask myself this very intensely just the other day.

My buddy Jason and I had camped along the North side of Clochuck Lake.  He set out about 40 minutes ahead of me for Aasgard Pass and I figured that I could make up some time by crossing the lake directly as opposed to contouring closer to the shoreline as he had done (and as we had done the day before without incident).  So I consider the circumstances (thick ice near the shore, >6K', February) and start across the lake.  There is no snow cover apart from the shore area so I am able to see the ice clearly.  I bounce now and again and things seem sound.  I cross the occasional frozen crack which is fine but they seem to get more and more frequent.  I do a little zig and zag to avoid treading directly over the intersections of cracks but they are getting frequent and hard to avoid.  I considered turning back a time or two but opted to stay the course.  As I am nearing the middle of the lake (it somehow seems a lot bigger from this vantage) I am beginning to see water running in some of the cracks as I cross over them.  The ice is also noticeably darker underfoot.  These observations elevate my concern to fear.  I stop..... listen...... and take a couple of deep breaths.  I rationalize that I had had too much espresso at camp and and that must explain why my heart is racing and I am sweating.  Everything is cool.  I just need to keep going.  Maybe I'll unbuckle my pack just in case.  I unbuckle my boots as well.  The whippet will work good to pull myself out.  Everything is cool.


Jason snaps a pick of me maintaining my cool while on (thin?) ice

I decided to adjust my course a few degrees E as it is now the most direct line to shore.  I begin moving slowly as to be best prepared to react if the ice fails before me.  Should I move faster as to minimize my exposure at a weak point?  Maybe, plus I'll be the hell out of here.  I move moderately quickly taking care to stride fluently and evenly.  I was not at ease until I was nearly to the shore.

In retrospect, I really do not know how sketchy the situation really was only that I didn't know that it wasn't.  I never felt like I was on  floating pieces of ice but the liquid water in the cracks and the dark areas could not have been good signs.  I wasn't so much scared as I was aware that I  had unnecessarily put myself at risk and felt stupid.  I'm not sure what I learned other than I would like to have a better frame of reference for evaluating the stability of frozen lakes.

...this proved only a warm up for the icy dangers of Aasgard Pass.  Don't drink too much espresso before exposure.  It can mess with your cool.

Ok Gary that is a spooky story. Were there any telltale signs at all in the snowcover?
Going under water with a heavy pack and locked dynafit toepieces is not on my agenda but skiing across frozen lakes is one of my favorite parts of winter.

You got that right, Ron. To use a golfing term, that would be an unplayable lie. Really, it had been colder than normal for weeks and as I skied onto the lake there were these big longwave drifts and plenty of snow. I wasn't concerned in the least.

Big Snow, I think the ice settling and being overrun by water wasn't the case here. As far as I could tell, there was only 4" of slushy snow over the water as I reached the middle (actually SE section) of the lake.

Coming out from Bow Hut one time I crossed Bow Lake where the winter-long, hardened ski track was the only part of the ice above the water. But the aqua blue color still seemed to indicate thick  ice. I was in the lead in an ACMG course and before committing asked the very experienced Bernie Schiesser, who was the guide/examiner, if he thought it was still safe. Bernie answered in the affirmative. With a strong tailwind I unfurled my ski parka and glided across with my group (and Bernie) in a few minutes. The other ACMG group wallowed around Bow Lake in disgusting, isothermal depth hoar that caused the ski tips to remain above a crust while the ski tails sunk to the ground - like skiing up a 30 degree incline in depth hoar. It took the other group about an hour. I felt smug, but having Bernie there was our big advantage.

Snow Bell, It's not a very comforting feeling is it? I guess lake ice is one of those things that I don't know very much about.

You guys are really disturbing my constitution with these stories. It's been a couple of seasons but Michael and I skied across the middle of Colchuck right around this time of year without a second thought - just seemed the natural way to go. I wouldn't have considered geothermal activity to be an issue there, and I always rested my mind with the theory that the ice would be thinner near the shore where it is shallow, excepting if there was sun protection on the shore where you got on the ice, so I guess I always imagined seeing the trouble signs before you got to the middle. What was the weather like? You mentioned the pass was icy...
I am going to just ignore your warning about espresso.