As was recommended from last week I have made a nice little graph of the ice data from this recent measurements. The measurements in this week's chart are in inches.
The ice became fully bonded over the past week. The average thickness this week among all of the lakes was 8 1/2 inches. This winter is shaping up to be pretty cold indeed. Last year the average ice thickness was 7 5/8.
The ice was generally safe everywhere except for two distinct and notable spot that historically are never safe: Lake Street Bridge and Lake Harriet "soft spot." The Lake Harriet soft spot is marked with a bouy, but the Lake Street Bridge is very much not stable and portaging is needed to get between Bde Maka Ska and Lake of the Isles. This year there is no signage under Lake Street Bridge, and this bridge is typically the "most visited of the lakes" as it is very pretty, but stay away. The Lake of the Isles bridge are safe to take pictures with though.
I am still working on a website for the ice report, and I am taking my time with it, ice report is also going to be making some advertisements encouraging people to go outside more in the winter.
| Lake / Location | # Samples (This Week) | Min | Max | Avg (≈) | Growth (≈) | Notes |
|---|---|---|---|---|---|---|
| Cedar Lake | 6 | 6 5/8 | 9 1/4 | 7 3/4 | +3 3/8 | Major consolidation after flooding |
| Cedar Lake Channel | 1 | 9 1/4 | 9 1/4 | 9 1/4 | N/A | Not measured last week |
| Burnham Bridge | 1 | 7 1/4 | 7 1/4 | 7 1/4 | N/A | Not measured last week |
| Kenilworth Lagoon | 1 | 7 3/4 | 7 3/4 | 7 3/4 | +3/4 | Sheltered, slow growth |
| Lake of the Isles (main) | 7 | 8 1/8 | 10 | 9 1/2 | +3 3/8 | Big jump, now very uniform |
| East Isles Pkwy Bridge | 1 | 9 7/8 | 9 7/8 | 9 7/8 | N/A | Not measured last week |
| Midtown Greenway Bridge | 1 | 7 1/8 | 7 1/8 | 7 1/8 | N/A | Not measured last week |
| Lake St Bridge | 1 | 4 3/8 | 4 3/8 | 4 3/8 ⚠️ | N/A | Do not cross under Lake Street |
| Bde Maka Ska | 6 | 8 | 8 5/8 | 8 1/4 | +2 1/8 | Even, steady growth |
| Lake Harriet | 6 | 7 5/8 | 9 1/4 | 8 1/2 | +2 | Variability shrinking |
| Lake Nokomis | 5 | 8 3/4 | 10 3/8 | 9 1/2 | +3 | Fastest growth overall |
| Lake Hiawatha | 4 | 8 1/2 | 9 1/4 | 8 7/8 | +3.3 | Dangerous spots mostly healed |
| Loring Pond | 3 | 9 1/8 | 9 1/2 | 9 1/2 | +1.1 | Already strong, now rock solid |
I appreciate your dedication to this and to keeping us informed!
Where can I get or rent one of those ice sail things? I'd love to try that out sometime.
I have no idea, I think most of the people who do it own and build their setup
I doubt anyplace rents then out. It's a pretty inherently dangerous sport. One of my cousins does it and he's got some crazy stories about crashes.
They're privately owned, but ice boaters are friendly and eager to talk about the sport. The best way to get into it is to make some friends. If you see them out, you could always approach and wave and say you'd like to watch/learn. Unlikely that a DN owner would let you try it, as they're single-handed, but sometimes you'll find a Nite class boat out there which is a two-man. Bring some beers to share 😉
It's sailing, so you definitely need to know the basics of how that works.
I have been walking on frozen lakes since I was a kid. As a grown up now I’m taking my own kids out on the lake. But sometimes it freaks me out to be walking over the lake, especially when there’s a big crack or a dark spot. How do you know when ice isn’t safe? Is there ever like a random thin spot? I go out on bde maka ska.
It depends, but temperature is a major factor if the night doesn’t get below freezing for several days the ice will weaken, but it takes about 2 to 3 weeks before this will weaken it enough to make unsafe.
When it gets warm out the ice will undergo a process known as “candling” in which small natural cracks expand resulting in ice that “cubes” instead of remaining strong. And when it gets warm the ice tends to form “cobwebs” which are small holes like from an ice fisher in which the ice does not heal overnight. It usually does not simply melt completely away like an ice cube however, and the cracks in the ice grow until large chunks break and float away from each other. On very large lakes, like Red lake in the north, these large ice chunks can still support significant weight and there have been incidents of entire groups of people having to be rescued off these rogue icebergs.
The ice currently is very well formed and would take about 2-3 weeks of intense continuous warmth to destabilize it
Thanks for the reply!
Thank you for your service
Much appreciated. Do you know—what causes the Lake Harriet soft spot?
In order to make the chain of lakes an actual chain, water from Bde Maka Ska is pumped into Lake Harriet, where this pump dumps, is where the lake Harriet soft spot is
I believe they did some modifications in recent years to switch that last operational segment of the old pumping system for lake level maintenance to a gravity feed in the last couple of years when they daylighted that little portion of the original overland connection. If it works, the soft spot should be as soft as ever.
It was the one remaining pump from the Missississippi to Bassetts Creek to Birch Pond to Brownie Lake, through Cedar, Isles and Bde Maka Ska, then some water from Bde Maka Ska uphill to Jo Pond, the rest to Harriet, then on to Minnehaha Creek and Minnehaha Falls pipeline that was taken offline in 1991.
Oh wow, I had no idea – thank you. I live right off the lake and walk by that almost every day.
Cool! I have no need for this personally but found it interesting, thanks !
Thanks for your efforts.
It would be helpful to include in your initial post something like "the ice is generally safe if there are at least N inches for M days" or whatever you think the safety criteria are. I see "8 1/2 inches" but I don't know what that means for safety in your opinion (or if there are objective guidelines somewhere).
There are very objective measures of the ice
According to the MNDNR 8 1/2 well enough to support a snowmobile for example. The ice is still growing and is the growing is indicative or healthy strong ice. As spring approaches the ice naturally and obviously stops growing, and even then it is still possible to measure the strength of the ice in terms of the standards on this chart https://www.dnr.state.mn.us/safety/ice/thickness.html
As a general rule the ice is safe for walking at more than 4 inches.
The ice will likely destabilise around the beginning on March or end of February (unless we have a super cold winter).
The new website I will by releasing next week will have color coding for its map
Thanks.
Given the warm temperatures we've had with melting, I found this quote interesting:
"When a layer of snow melts and refreezes on top of lake ice, it creates white ice, only about half as strong as new, clear ice. Double the above thickness guidelines when traveling on white ice."