Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Snow removal over ice

Bill, we finally had courage to put the snow removal machine (4 wheeler with plow) on the ice. We had heat trapped under heavy layer of snow since early December and edges stayed soft. Even the bitter cold wouldn't firm up the edges. Finally some of the snow melted and the cold won out. We have layers of ice, frozen snow and then ice on top. Got the ice cleared and pond flooded for skating finally in February!! Need a few more floodings to get to that super smooth ice. I'm happy last weekend that the sun had 2 days of direct access through clear ice to help whatever plants are in there to make some oxygen.

At a small pond down the road the nephews got to do some ice fishing and tied into a skinny NP. It is lots of fun for the kids to be able to walk where they want and see the fish through the hole in the ice.

I love reading our "southern pond" reports, and our "northern pond" reports!

You being now set up for ice skating plus posting a pic of kids that caught a pike through the ice ... that is some Grade A northern pond reporting!

We are also now at 11” of ice in most spots. Water does not up well when I auger a hole in it to test. Oddly though, when I made a second hole, the water oddly bounced in a strange way in both holes. I may create a path with the tractor to get the ATV on the ice, but it doesn’t seem worth the trouble as we are supposed to have another 3-6” tomorrow evening, and the temps are supposed to drop to -4F with wind, making it absolutely miserable to be out. Then next week a few slightly warmer days with a few inches of snow each day.

Sometimes you just have to give up on the skating.

I was thinking the same thing. I'm getting ready to resume feeding next week (75day/55night temps) and they're ice skating...haha.

Since I have a groundwater pond, the ice is typically 50%-60% as thick as the ice on the local lake. A lake 25 miles away had roughly 8" snow, 1" ice, 2" water then 6" ice. I keep a hole open that is about 30' in diameter at one end of the pond and that seems to be enough for the fish there. I have not had a winterkill in the pond. Two years ago when the pond area wend from 1 ac to 5/8 ac but the biomass didn't change much, I would run the aerator in the deepest part of the pond just enough to open up the ice there, then shut it back off. I kept the winter diffuser running 24/7. I was on pins and needles but made it through the winter with only removing roughly 100# of fish from the pond via angling.

I read this post and took it to heart. I live not too far from Liquidsquid and my 1.3 acre pond is under about 8" of mostly fluffy snow. I have two aerators running in shallow water but we have been consistently near or below 0 at night so the open areas have shrunk to about 20' across each. I have over 12" of ice right now so I took my small utility tractor and cleared maybe 1/3 acre about 200' from the open holes. Like Liquidsquid, we had a partial thaw and refreeze and you can see the pattern in the exposed ice. I should buy an O2 meter, but I'm too cheap. We'll just have to see if we avoid fish kill. One good sign is that last Saturday I caught a 12.3oz 11-1/4" YP full of eggs, so something is alive under there.

I'd really love to know if the limited holes from aeration were good enough, or should I plow every winter. Sounds like a good study.

One more comment: the white ring near the bottom of the picture is where I angered. I didn't see any water coming up through. To keep the ice level I keep one of the aerators at the spillway and the spillway seems to run all winter under the snow & ice and keeps the pond fairly constant until ice out.

Retired on40. With your precautions you should not have any winterkill.

Bill (and all others),

I am a big believer in "half a loaf is better than none".

If you can only do "partial aeration" of a pond, and the pond is getting close to winterkill low oxygen conditions, are the fish capable of sensing the column of aerated water and congregating there until conditions improve?

Bill, I trust that you are right. FishinRod, do we know the rate of lateral oxygen dispersion/diffusion in a body of water? Much of it must be due to physical mixing of the water, but oxygen will diffuse due to the concentration gradient as well. How well do Fish sense that gradient?

(The diffusion coefficient of oxygen in water at 5C is around 1×10-5cm2/s, one just has to apply Fick's law to a body of water with a 20' diameter cylinder saturated with O2, and make some assumptions around O2 consumption, but I haven't done that in 40 years)

Snow.and ice? Never seen it.

My first response was no, but then due to the easier movement of O2 in the water in winter, I guess it would depend on how far away the aerated area was from the non aerated area. It will not help in summer, so a "partial aeration" can still result in a partial summer kill.

Case in point. 18 acre HOA lake. Highly Eutrophic, 10' depth max. They experienced multiple winter kills and summer kills over the years. No wake zone on the whole lake. Due to the layout of the lake, the available electric and their budget, they were only able to afford an aeration system that would aerate 9 acres. The aeration system was installed and covered 9 acres (roughly a mile of self-sink aeration tubing was used). Mid August, hot temps, no wind, high phytoplankton count and high underwater weed population. I was called back because of a summer kill roughly 3 months after installing the aeration system in half of the lake. In doing a boat survey, all of the fish that died were in the half of the lake that did not have aeration. (no wind to move the dead fish around)

I'm glad that I hot footed it over there when I got the phone call. The next day the wind came up and blew dead fish over to the aerated side of the lake and the HOA president got calls that the aeration system wasn't working. I had him in the boat when I did the boat survey so he saw first hand where the fish died and he observed that in fact the aeration system did do what it was supposed to do. .

Esshup, you present compelling evidence that an aerator has a limited effective area of impact.

As you stated, "I guess it would depend on how far away the aerated area was from the non aerated area"
Without significant inflow, under the winter ice there should be little physical movement of water and it would seem that oxygen concentration would be limited (as Bill C points out) by light induced oxygen production, consumption, and any dispersion/diffusion from an aerated area. When we use aeration and create open areas in the ice, my question is, "how large an area is typically impacted by limited mixing and diffusion?" Or, "If the cold water in the open hole has a concentration of 13-14 mg/L of oxygen, at steady state, how far from the hole must you be before the oxygen level is lethal, assuming no additional sources of oxygen?"

Problem is that I don't know the consumption rate under the ice, since without consumption the whole pond would ultimately be oxygen saturated. Maybe there is a good estimate of consumption based on bio-load.

Question was:
My commentary - To my knowledge very little testing has been done for the amount of water current movement that occurs from a bottom diffuser aerator. Depth placement of the diffuser I think will have a significant influence on how far the diffuser currents spread. One has to keep in mind that water that is at a uniform 39F will move and spread a lot further distance compared to summer water temperatures. IMO the water will spread a lot further than one would expect.

Solar radiation through the iced shoreling areas causes water current movement.


After thinking about this especially during iced winter conditions, I believe that the sound of the rising bubble plume and is perceived a long distance by fish. I don't think we realize how sensitive fish are to their surroundings. Fish can readily feel water movement, current and underwater sounds. This is the habitat that they grow up in. This is their adapted world. For them, sensitivity is critical to survival. IMO bubbling action at one end of a 1 acre ice covered pond will be perceived at the opposite end of the pond. The bubbling sound in the middle of a 5 acre pond during calm winter ice cover may even be perceived throughout the entire pond.

Bill, you are correct about how sensitive the fish are. In the summer, I can walk to the feeder and the fish can "hear" me walking. They start swimming to the feeder because they know I will throw out a couple handfuls of food.

While I still have ice on the pond, I can do a test. There is open water to the shore in my pond from the winter diffuser. I have 7" ice on the pond away from that open hole. I can take a 10' piece of PVC pipe, hang my O2 meter sensor from it and take an O2 reading. Then I can take readings away from the open water all across the pond.

My question to you is at what water depth do you think I should test the O2 concentration in the open hole? I will have to take the sensor to the PVC pipe and hold it out from shore. I have depth markings on the sensor cable.

FWIW, I am catching Bluegill 12"-18" off the bottom in 11 to 12 feet of water........

esshup - DO concentration in the aerated ice free area should be uniform top to bottom and toward the high concentration of above 9-10 mg/L. For DO readings all across the pond, I would start at the furthest area away from the open hole. If DO reading near the bottom is very close to what it was in the ice free area, then IMO DO is uniform pretty much throughout the pond. Fish activity helps to somewhat distribute water currents. However if you want to be most accuruate, then check DO at some midway points. Lowest DO concentrations should be near or within 12" of the bottom.

Thanks for the offer to document some actual data esshup!

Looking forward to your results.

Notwithstanding your diffuser data, I would like to see what the DO is at the far corner of your pond where the BG are apparently happy enough in their conditions to eat your bait.

I did take an O2 reading on my pond yesterday. I ran the aerator for the past week, but shut it off 48 hours ago.

I took the following O2 measurements roughly 140 feet away from the open hole that the winter diffuser made. I would have taken readings further away, but the ice was too sketchy and I really didn't feel like going for a swim.

I was ice fishing on Sunday and fish were seen on the sonar right on the bottom of the pond in 12' of water all the way up to about 4' below the ice. Today is Tuesday and it really warmed up - temps are in the upper 50's today and yesterday they were in the low 60's with full sun. Saturday I had 7" ice, Sunday it was in the upper 40's with full sun and the ice thickness was 6".

2' below the water surface the O2 was 12.71mg/L
4' below the water surface the O2 was 12.71 mg/L
6' below the water surface the O2 was 12.65 mg/L

Water temp varied from 40.0°F right below the ice to 39.5°F at 6' depth.

These readings were taken approximately 135 feet from the edge of the ice where the winter diffuser is placed. The winter diffuser is placed 3' below the water surface.

Maximum pond depth now is 12'.

My pond is a groundwater pond, with a sandy pond bottom. There is a high water table, but the pond is down approximately 6' from full pool. .

I would not be concerned to have the winter diffusers placed 400 feet apart (at least in my pond). My pond was renovated in 2008, so it's going on 18 years old. It does get a bunch of leaves blowing into it, and I feed the fish approximately 80 pounds of fish food per month from April/May until mid November.

I couldn't find this thread so I started one about this data in the aeration part of the forum. That thread is here: O2 readings away from the winter diffuser.

Thanks essup!

Those are exemplary DO numbers.

Is your ice clear and your plants have started photosynthesizing?

Or does aeration in a mostly ice-covered pond have some efficient mechanism for transporting and circulating oxygenated water? (I think "yes" based on your sparse experimental data.)


P.S. You should have a pond full of happy fishes!

VERY few plants in the pond. Some CLPW growing that will get whacked by Fluridone - thanks for the reminder I need to put it in soon. Other than that there might be some FA growing but the water is extremely clear - 12' visibility. There is about 3" of milk colored ice and there was a few inches of clear ice under that. It's a ground water pond, so the temps are warmer than in a non-ground water pond.

There was a couple foot area of ice melted around the pier yesterday and I could see a Golden Rainbow Trout swimming around at about 4' water depth. It's 65°F, sunny and windy now. 20 mph winds. So I expect the ice to be mostly gone with the rain expected tonight and tomorrow. Just in time for more snow on the weekend.

Those are very impressive DO values! You are essentially at saturation for those temps.

I cleared snow from about 10-15% of my pond to let some light penetration come through in hopes to keep my DO levels up. I tested it about a week and a half ago and got 10ppm at 6" below the ice. I was surprised it was that high, particularly with very little aquatic vegetation and no aeration. What I wish I had done was to get a temperature and also to check the DO levels before I cleared the snow off to see if clearing it made a measurable impact.

I'm using the CHEMetrics DO kit rather than a meter, so I also wondered if the water temp effected the accuracy of the results. I reached out to the company to try to get some insight. Although they didn't have a concrete answer, they said that it may take up to five minutes for the reaction to complete rather than two minutes at "room temperature".

I'd like to get out there again to test the DO at various depths below the ice. If I come up with any interesting data, I'll report back here to share it with the group.

Just a follow up: In early spring, I found four dead large bg after heavy rain that finally filled the pond after a very dry winter. Not sure if they died under the snow covered ice or from the rain rapidly changing the water chemistry. Was concerned about a wider fish kill, but my neighbor recently fished the pond and caught a bunch of large bg and some eating sized lmb. Looks like the good advice here about trying to clear snow from a small percentage of the ice likely did the job. The snow was on the ice for a couple weeks so we dodged a bullet. Thanks to the experts here!