Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? bio dredging, does it work?

Some back ground first, I'm in South Western Alberta, Canada- similar climate to northern Montana.Recently moved onto a 4 acre property with a 0.4 acre pond. Most of the pond is 3-4' deep, however closer to the dam it's 6-8 ft deep. It's fed from a spring 2-4 gallon per min year round. Maintains level thru seepage but has overflow set up for spring run off and rain storms. Pond is 22 years old. (according to my records)

1st year: Pond is stinky (Sulphur) and full of Algae. Well water on the property is stinky as well. Did some research and determined pond had become anaerobic and had 8-12" of muck that was continuing to accumulate.
Added a small aerator (much too small from ebay) and ~20 2 lb rainbow trout and muck bacteria. we had a 1 in 100 year very cold winter, aeration hole froze. In the spring the fish kill was obvious- even small minnows in the pond were dead (I've no idea how they got there)

2nd Year: Added a much larger aerator, dye, and muck pellets. And 30 12" trout. Dye didn't last 2 days (water
exchange) and all the trout were eaten by blue heron, and cormorants. Added decoys: coyote, heron and bald eagle. Seems to have helped. Stocked again with 45 12" trout. Winter was more normal and aeration hole stayed open (Except for a few days) Trout survived.

3rd year: added 12 more 8" trout. Well water quality is improving in the house and the dogs no longer smell like rotten eggs when they come out of the pond. Trout are growing nicely and I'm supplementing their diet with floating feed. 2 floaters this summer. I'm noticing some pond depth returning maybe. Still having algae blooms.

I'd love to dredge the entire pond with a long stick, however the layout is not great for this. yard finishing like fire pit, gazebo and horse fencing make it a really big deal never mind the expense of it. The other side is woods and a steep embankment.

I believe I'm having success turning this pond aerobic. Question is can I make significant ground 'bio dredging'
Any other tips/insights would be most appreciated. I don't mind spending years at this if I see improvements. I like the biodiversity the plants and shallow areas provide good habitat for insects and larvae. I've seen the trout in the shallows feeding naturally.

Dan

Hey Danno, your post has been live for 2 days and you've gotten no replies, so I'll give it a shot. From what I hear, the experts on here aren't super fond of those "muck removing pellets". In theory, they're adding beneficial bacteria that's already in your pond. Seeing how shallow your pond is for the climate you live in, I'd wager that the pellets won't be enough to give your pond back the depth it needs. 3-4' average and 6-8' max depths in a Canadian pond is risky business, but I'm sure you're aware of that, hence your desire to make it deeper. I think the experts recommend that your deepest parts should account for 25% of the surface area of your pond. In your case, you said there's only a small area that might be 8'. With average depths in the 3-4' range, I think you will always be dealing with issues in the winter. Also remember, that most ponds accumulate about an inch of muck per year. In 10-12 years, your 6-8' max depth is now 5-7' and even more susceptible to fish kills.

I hope some experts can chime in and give you some better news than I can give you, lol. If I had to guess, I'm going to say that they'll likely tell you that draining and digging will be your best option.

I have thought about trying to dredge some. I was thinking about building a floating platform and putting a trash pump on the platform. Use a long pipe to run the suction hose and run the outlet hose out into the woods other side of the dam. It wouldn't be perfect and it WOULD take years in my case, but it would be a start. Haven't made it past an idea in my head.

EDIT: In my non professional opinion.... you gotta be careful adding bacteria pellets to a pond that freezes over. Bacteria is what is going to consume most of your O2 in the Winter. Adding more bacteria just adds more O2 demand. Just out of curiosity - did you measure water temps at all during ice over?

Others in recent posts on this forum have had great success with good quality muck removal pellets. They are very costly and work very slowly. They work much better in warm water (June through Sept) combined with bottom agitation to stir up settled solids and with aeration to add oxygen to the lower levels of water. They can remove 4-6" of muck in some cases per year. Since your pond is 0.4 acre a $350 investment into 25 pounds of muck pellets should treat your pond several times over in the warm weather season.

Your dredging idea Will work just takes lot's of hours. I use a 3" trash pump set on the bank and reduce the pipe to 2" I run pvc pipe out in the pond and then put flexible intake pipe on it. I pump up to an above ground pool then I let it settle and drain the water back to my bait fish pond. I have a 4" pipe out the bottom to a pit for the muck. Works pretty well and I save my water.

On the flexible hose I put another piece of pvc with holes drilled in it to work into the muck.

They make huge filter bags, pump the water into the bag, let the water immediately go back to the pond, but all the sediment stays in the bags.

I tried to find something like that but I couldn't find anything really large. I tried to build a fence with filter fabric but when I got much muck behind it it would leak under the fence or push it over.

Is 15'x25' large enough?

https://www.erosioncontrol-products.com/dewateringbags.html

That might be ok but how do you handle the muck in the bag once it's full?

You can leave it dry and use a tractor with FEL or skid steer or excavator. It's out of the water on dry land so the water will continue to seep out of the bag. You can't move it immediately, but after 4-6 or more months depending on the weather you can expect it to be like wet dirt.

Was going to do a job that had a nursery next to the pond, they were going to leave the muck in the bag and use it the following year as soil. Ended up not doing the job due to price...

I don't doubt the price was high. I pump mine to a pool let it settle and drain the water back to a bait fish pond then dump the muck through a 4" pipe to a pit and then make topsoil out of it.no extra tractor work and no long wait times to move it

It does make fine topsoil I mix it with compost and manure and shavings from stall cleaning