Moving to silted ponds... help!!!

[johan]

Hello,

I'm moving to a property with some ponds in a poor state, and I'd love some advice! The property that I'm moving to has a small, slow flowing natural stream running through the length of the garden, and three ponds. There is a Victorian clay lined pool at the top (10m x 10m), a large natural pool in the middle (30m x 30m) and a formal square pool at the bottom (10m x 10m).

These pools are no deeper than one or so foot at best, being almost completely silted up by non-maintenance for more than 100 years. On top of that, there are other ponds higher up the stream, and creating those has also moved a lot of silt into the ones that I'm taking possession of. The top pond is completely in shade (forest) and the black silt has little plant growth in it. All looks a bit stagnant and smelly. The middle and lower ponds are in full sun - some plant growth but almost no submerged plants.

What would your advice be to manage/change this sensibly? I don't plan on fixing this overnight and I'm not averse to buying an agitation pump to move the silt elsewhere on the land. The goal would be healthy ponds with plenty of underwater and marginal plants to encourage insect and invertebrate life. The area is clay, the country is Uk (ie temperate) What would grow in shade and allow me to reclaim some of the dead silt areas - are there and specific techniques that people have used and can recommend?

Thanks!

This is the middle pond:

 

[MitchM]

If there's slow moving stream flow through the existing ponds, my first reaction is to do nothing and observe/investigate some more.
You mention that creating upper ponds higher up in the stream created a lot of silt for the ones you are taking possession of - were these ponds created recently?
More pictures would be good. Stream entrance/exit areas specifically. It looks like a great area for wildlife.
Would there be a Google Maps overview shot of the property that you could provide? (without any identifying information)

I also have a natural pond with a slow moving stream and find that water cloudiness is a seasonal event.

.

 

[johan]

Thanks Mitch - good advice and to answer your questions: there are several village properties upstream from our new house. Immediately upstream (ie next to us) there are 2 houses with 20m x 20m ponds, but about 1/2 a mile upstream there's a fella who has created a 100m x 50m lake from this stream, in the last 5 years.

The house upstream but one from us had a machine a couple of years ago to clear out silt, but the considered opinion round the village is that he did it badly and the silt all flowed back into his pond.

I don't have pictures on me of specifically exits and entrances, but they're all quite small. This is the very silted over upper pond. Our property includes the foreground bridge - the people selling say that they used to have a boat and paddle under the bridge, but it looks pretty blocked up with debris and silt to me now. You can see though that there's a lot of silt and few plants - I'd like to change that!!

Next is the only picture of an exit I have on me, from the large middle pond/lake to the lower ornamental pool (it was a spring-fed swimming pool once upon a time 100 years ago):

There are some neglected koi pottering around in there, but that's about it. No depth to the water, murky.

Google maps isn't all that helpful because of the mature trees covering a large part of the property. I've marked up my ponds in lightest blue, and the two neighbour ponds that I refer to in a slightly darker blue. What I refer to as the "lower" pond is the one at the top of this picture, the streams runs from bottom to top

 

[MoonShadows]

Looks like a beautiful piece of property! You've come to the right place for help. There are experienced, friendly folks here that will help you out. Looks like a big project ahead for you.

 

[Meyer Jordan]

Do you have any idea of what the typical water velocity may be?

 

[johan]

View attachment 102191

Looks like a beautiful piece of property! You've come to the right place for help. There are experienced, friendly folks here that will help you out. Looks like a big project ahead for you.

Thank you moonshadows! I'm not really completely new to this forum and ponding though, albeit my previous experience is on a wayyyy smaller scale

 

[MoonShadows]

OOPS! I never checked your post count...sorry. Guess it was the fact that you were moving to a new house with "new" ponds for you that threw me off.

 

[johan]

Do you have any idea of what the typical water velocity may be?

Minimal, it barely trickles along. The water actually comes off a set of hills about a mile in the distance, my village is in the valley. Rough estimate, the stream is something like a gallon a second?

 

[Meyer Jordan]

Minimal, it barely trickles along. The water actually comes off a set of hills about a mile in the distance, my village is in the valley. Rough estimate, the stream is something like a gallon a second?

At that level of flow, all of the ponds upstream from your location are probably extremely heavily silted.
This would explain the accumulation in your ponds, although run-off may also be a factor.
In order for you to control the level of silting in your ponds, the ponds upstream must be addressed first as much of the TSS is now migrating far downstream to your property and beyond.
Your ponds can be dredged, but the silting will continue at an above average rate as long as the ponds upstream are neglected.

 

[johan]

Yes I'm sure you're right, I had long suspected that the things upstream are a large part of the problem. It remains to be seen if I can get cooperation from the other landowners. Word on the street is that it's unlikely, the pond owners in the village are quite insular - especially the person who owns the pond adjacent to ours.

That said, the ponds on our land have never been dredged, and they've been around since 1875 or so. So if I do dredge them, you'd hope that you might be able to leave them alone for 25-50 years before they needed doing again.

Anyone have any experience with buying and running something like this agitator pump? I can go get some guys in to do this but they'll charge £10k, this is £3k and I can reuse it as and when

 

[MoonShadows]

LOL...Johan...I see you just amended your signature to include the new pond project...or as you call it the new INSANE new Pond Project!

 

[johan]

Yeah, and that's an optimistic opinion!

 

[Meyer Jordan]

Yes I'm sure you're right, I had long suspected that the things upstream are a large part of the problem. It remains to be seen if I can get cooperation from the other landowners. Word on the street is that it's unlikely, the pond owners in the village are quite insular - especially the person who owns the pond adjacent to ours.

That said, the ponds on our land have never been dredged, and they've been around since 1875 or so. So if I do dredge them, you'd hope that you might be able to leave them alone for 25-50 years before they needed doing again.

Anyone have any experience with buying and running something like this agitator pump? I can go get some guys in to do this but they'll charge £10k, this is £3k and I can reuse it as and when

This slurry pump may or may not be the answer that you are seeking.
The pump you have indicated has a base flow rate of 1300 lph although there is a smaller version that has a base rate of 700 lph. The problem arises that either pump will drain a pond faster than it can refill given the 240 lph flow rate from the stream.
This would leave you with two (2) options.
1) Pump out what sediment that you can, wait for pond to refill, resume pumping, repeat, repeat, repeat for quite a long time to get all of the sediment. Or
2) Pump out what sediment that you can and before the pond can refill have a crew of strong backs on-hand with shovels and wheelbarrows to remove the sediment at a faster rate. Even this approach will take several stages before the desired amount of sediment is removed.

Was the £10k the cost for dredging all of the ponds or for each pond?

 

[johan]

This slurry pump may or may not be the answer that you are seeking.
The pump you have indicated has a base flow rate of 1300 lph although there is a smaller version that has a base rate of 700 lph. The problem arises that either pump will drain a pond faster than it can refill given the 240 lph flow rate from the stream.
This would leave you with two (2) options.
1) Pump out what sediment that you can, wait for pond to refill, resume pumping, repeat, repeat, repeat for quite a long time to get all of the sediment. Or
2) Pump out what sediment that you can and before the pond can refill have a crew of strong backs on-hand with shovels and wheelbarrows to remove the sediment at a faster rate. Even this approach will take several stages before the desired amount of sediment is removed.

Ahhhhhhhhh - good maths, thanks. Yes you've exposed an obvious problem! That said, I suspect I'll need to overengineer the pump because I want to be able to pump the silt out onto our land, some distance away from the stream. Can't have the stuff going back into the water at the first sign of rain

Was the £10k the cost for dredging all of the ponds or for each pond?

Combined

 

[Stephen T.]

My wife and I maintained a very remote property that had 6 ponds, the largest was 13 acres. There was a ditch feeding it, about 1/4 mile long and it was not accessible with any large equipment. Along the way was a pond that silted up badly, one we used for rearing fingerling trout, before release into the ponds. About 50 feet away, but only a foot or less higher was a large flat grassy area. We used a 4" gold dredge to suck out the silt. It did move a lot of water though. The dredge had no problem moving large quantities of silt and plants with a small lift, to distances of over 50'. Running back into the hole, after 50 feet of grass filter, pretty much settled the silt out of the water.

If you dig out in one area at first, till you run low on water, then let it fill and do it again, in a few hours of off and on work, you'll have a large reservoir of water to work from.

A settling pond ahead of the inlet would make things simpler, someplace where the silt could be easily cleaned out as needed.

That's already a beautiful spot, you're very lucky to have it!

Steve