Pond Boss Forums INTRO New Forum Member Introduction Alum treatment for Winterkill?

I am new to the forum so let me know if I misplaced this post or leave any thing out.

We have a dam in South Dakota that has winterkilled the last three winters despite being very deep and keeping the ice relatively clean and clear. We have tried to run some small aerators but have trouble keeping them running properly and keeping snow from blowing in and crusting over the hole I am pretty sure we have a problem with excess nutrients (phos).

I am wondering if it would be possible/feasible/effective to address the source of the problem, excess nutrients, with an aluminum treatment. Rather than using aerators, which seems like a cover up for the larger problem.

Some back ground information: Dam was built in 1999. Currently covers 12 acres. Deepest point it 32 feet. Average depth is probably 16 ft. The water surface is not very protected so there is a lot of wave action when we have wind.

We would greatly appreciate any input from some one who has some experiece with alum, or any other ideas or insights.

PB friends, we know that the pond is deep, and so an alum treatment might indeed lock up some nutrients (P) as it precipitates and maybe it will stay on the bottom. I have never been involved with an alum treatment. So, we'd like to hear from those of you who have used it. Can we expect an improvement in water quality (lower productivity and decreased oxygen demand in the winter under ice cover) after a treatment? What is the cost of a treatment for a water body of this size (so we can compare it to other treatment options)?

Many thanks!!

L.Mack Welcome aboard. I would suggest a representative water sample taken and test for the obvious,PH alkalinity,TDS No3 P4 etc. Then see what your options are. Simply tossing alum at it may be a "shotgun" approach not needed or wanted from a PH standpoint.I would also address the aeration you have been using as that may be part of your problem .I assume you ice up for several months per year. Lastly what type of fish and size (age) have been winter killed in the past.

Your geography and site-variables are far outside of my personal experience, but I agree with Ted that your focus should be placed on aeration - and more specifically, "thermal destratification" of the water-column.
IMO, the significant depth of water, relative to the lake's surface-area, poses a far greater issue (as a contributor to thermal/oxygen stratification) than do the phosphorus levels.
Also, reducing the lake's available phosphorus levels would undoubtedly impact food-chain productivity (i.e. creating a new problem while attempting to correct another).
Lastly, it would require a lot of product, expen$ive freight and labor to execute an AlSO4 treatment on the scale needed to offer any reduction in available P; AND it would not alleviate any fish-kills caused by thermal/oxygen stratification.
IMO, destratification-efforts are likely to offer a much better return on the investment.

Here is a limnological approach. First we should find out what features are causing the depletion of DO? Is it due mostly to accumulations of windblown organic inputs allochthonously (external) or autochthonously (internally produced) materials. Are there secchi disk or water clarity measurements for this pond? Are there excess fertility issues in this pond? Alum will work primarily for helping to lower phosphorus and reducing the internal organic production from phytoplankton, but not for the reducing DO from decay of external organic sources nor from excessive submerged weed growths.

Yes we have ice cover for a few months usually. Unfortunately we get snow cover with it but we try to clear it off and get clear ice.

I did not keep up a journal for this project. I can tell you we had about 10 years of establishing our fish population before we had trouble. We had perch, bluegill, crappie, LMB and walleye that we stocked periodically. I don't believe the walleye were reproducing. All species and all year classes were lost. We have caught small perch since but no other species.

Bill: Maybe I prematurely eliminated the possibility of excessive fertility as a causal agent for BOD-spikes, but I rarely encounter relatively "new" lakes (dammed in '99) that suffer from eutrophication symptoms.
I also assumed that the lake's max and avg depths would limit the likelihood that excessive weed-growth (and subsequent decomposition) was an issue.
I guess we should ask LMack how the lake receives its water: presumably an extensive water-shed; and if so, what occupies the watershed that might contribute to rapid nutrient-loading.

There might be cold water algae blooms that die when snow cover and lack of wind occasionally eliminates sunlight penetration for long enough periods where decaying phytoplankton causes a large DO sag and a periodic winterkill occurs, but not regular annual winterkills. If the pond received good wind exposure the wind should be able to keep a significant portion of the ice blown free of snow.

Is this one of the ponds that Dr.Willis discussed in PB Mag where they were using windmills to minimize winter kill?

my family farms the ground above the dam. manure was applied to the field a year or two prior to the winterkill problems.that is the most likely source of the nutrient problem even though the water must flow through about 100 yards of grass before reaching the water.

About the same time prior to the winterkills we had a lot of muskrats inhabiting the area. They completely eliminated the cattails that surrounded our shore line could that have contributed to a release of nutrients?

We probably do need to take more steps to filter the water that runs in. But I am wondering how to take care of the nutrients that have already made it in.

We have not tested our water. We are assuming that it is nutrient problem due to the type of dam (very little topsoil was removed during construction) and the watershed coming from agricultural ground.

Likewise we have done no clarity tests. All we have had is our local watershed manager use a meter to test DO oxygen levels After we thought we had done avoid job of keeping the ice clear. He found DO under under 1 at about 12 ft if I remember correctly. The pH at that time was above neutral. I can't remember what it was for certain.

There I quite a bit of weed growth in the shallow areas. All submergent. I trapped most all of the muskrats but cattails are slow to recover.

Clarity has seemed to gone down considerably since the problem started. But as I said we have not tested it to give a score.

Bill, we always seem to have situations where we start with poor ice clarity or snow does settle then sticks to the ice. We do try to plow it off then I try to run water on top of the ice with my ice auger to get smooth clear ice on top.

This isn't a pond Dr. Willis is referring to.

I would not use alum unless you first do some routine dissolved phosphorus (soluable P or ortho P) tests as baseline information to determine if ortho P is the problem that could be reduced with an alum treatment. Total phos tests measure all phosphorus in the water column, dissolved and all that is bound in the living and dead organics in the sample which can amount to more than the ortho P. Bound P does not grow any plants until it is recycled and becomes available as ortho P.

I also think it would be informative to know what the phytoplankton density is 2 to 3 ft below ice, pre ice cover and during mid winter. This will tell you the potential for loss of DO when light penetration becomes limited to the point phytoplankton is dead & decomposing.

Here's my take on it. Sunlight comeing through the ice helps the plants that will grow under the ice in cold water produce O2 during the day. Same for phytoplankton. Then once night falls, they both need to use O2 to survive. O2 is lowest right before sunrise.

12 ac pond would be hard to aerate for the winter, but if you can, I would try. The diffusers should be put at 1/4 to 1/3 the deepest part in the pond, i.e. if the pond is 30' deep, the diffusers should be between 8-10 ft. below the surface. Leave them run 24/7. The more that you can put in, the better, but I have one in my pond that averages 3/4 ac during the winter. I haven't had a winter fishkill (yet).

It could be a number of things causing the fish to die. Lack of O2, build up of Hydrogen Sulfide in the water, etc. Keeping open areas in the ice where the water can contact the air will help mitigate that.

Using alum to remove nutrients, will in turn reduce the amount of phytoplankton and plants that use O2 during periods of no or low sunlight. On the flip side, there will be less to produce O2 during the day too. Removing fish, which consume O2 will also help reduce the BOD in the pond if there is a large fish biomass.

Yes, not having all those cattails in the pond contribute to the nutrients in the pond.

Bill, I have not seen the pond. It might be a candidate for Brian graeb's pond management class in the future. I have no doubt the pH is above 7. We just don't have acidic ponds and alkalinity is always high to very high. Of course, I have been known to be wrong on occasion! Ha! Thanks, guys. Keep the info coming.

Winter-ice represents a variable in which I have zero experience; but I'll theorize that the spreading of manure within the watershed - coupled with inadequate aeration/destratification - both played pivotal roles in the subsequent fish-kills.
I'll now grab my popcorn and watch from the cheering section.

Kelly, in the winter you want stratification. Warm water refuge for fish at the bottom of the pond. Water should be around 39°F there. Water can be in the low 40's directly under the ice, or below 39°F. If the diffusers are run from the deepest part of the pond in the winter, the whole pond can get too cold.

A lot of good information coming here. I still think the starting point is an accurate representative water test for all the "usual" levels. You need a baseline. Then develop a plan from there. As far as winter aeration if thin ice is not a concern I don't believe too complicated to design such a system. You may want to offer up what aeration components you currently have to see if that equipment can also be utilized to some degree. A 12 acre lake (pond) may only take 3 hp depending on the layout and a few other factors.

While you have found the solution from this discussion, I had faced a similar problem a few months ago. I had hired an expert at Alum in order to avoid taking the burden on research myself.

Does anybody knows about some Geo-Thermal Plants Sellers for homes? I have searched the web, but could not find anyone. This is the model I am looking forward to get.

snowed over

Yesterday morning we had nice clear ice for our first freeze over. 24 hours later a "nice" reflective layer of snow and frost. Let the hypoxia begin.

LM, check your PM's for some links to alum costs....