Large established pond - choked!

[G. Griffiths]

We have a spring fed pond, approximately 30 feet diameter, which was establised some 30 years ago. It has always been crystal clear, until now.

This year it has become choked with blanket weed and i simply cannot remove it quickly enough to keep on top of it. A lot of it is out of reach due to the pond size.

I cannot work out why this has suddenly happened after such a long period. the land from which the spring(s) derive have always been pasture with no fertilizers (apart from animals) being added.

The pool now looks so awful I'm on the verge of trying to fill it in!

Can anyone suggest a remedy please? I have tried sacks of barley straw - no effect.

 

[Lisak1]

Welcome! A good starting point is to remember that the algae is both a symptom and a remedy - it's telling you something is out of balance and whatever it is, it's handling it for you while you figure it out.

Does this pond have fish? Any kind of aeration or water movement? I'm assuming no filtration? Can you share some photos? What kind of animals are on the pasture?

We're here to help if we can - just need more details!

 

[Meyer Jordan]

First, how do you know for certain that the pasture is the only source for this spring water. Secondly, water from any underground source is subject to chemical change based on human activity at its origin and underground passage. In some cases it may take years for a contaminant to reappear at the spring-head.
If the source of the nutrients feeding the blanket weed can not be eliminated, then the only course of action is manual removal.Algae treatments will only 'kick-the-can-down-the-road' and offer no lasting cure.

 

[G. Griffiths]

thanks for the replies.

Fish - only sticklebacks. No aeration (I have read it makes no difference to blanket weed?) and no filtration. Water movement is negligible althought the throughput can easily exceed 1 gallon per minute depending on time of year/rainfall.

The springs are at the end of a ridge (rising to around 60 - 80 feet) extending about 1/2 mile or so. All the fields are permanent pasture supporting sheep and a few cattle and about 6 horses. None of this has changed for many decades and certainly not since we dug the pool some 30 years ago.

Manual removal is not an option - I have already spent many hours removing wheelbarrow loads over the last few months.

If a remedy can't be found I will either drastically reduce the size of the pool (estimated it around 25,000 gallons) and create bog borders or totally fill it in (will take many lorry loads of soil!).

Appreciate your kind help.

 

[Meyer Jordan]

thanks for the replies.

Fish - only sticklebacks. No aeration (I have read it makes no difference to blanket weed?) and no filtration. Water movement is negligible althought the throughput can easily exceed 1 gallon per minute depending on time of year/rainfall.

The springs are at the end of a ridge (rising to around 60 - 80 feet) extending about 1/2 mile or so. All the fields are permanent pasture supporting sheep and a few cattle and about 6 horses. None of this has changed for many decades and certainly not since we dug the pool some 30 years ago.

Manual removal is not an option - I have already spent many hours removing wheelbarrow loads over the last few months.

If a remedy can't be found I will either drastically reduce the size of the pool (estimated it around 25,000 gallons) and create bog borders or totally fill it in (will take many lorry loads of soil!).

Appreciate your kind help.

What plantings are now in place in and around the pond?

 

[MitchM]

It sounds like there has been an unusual amount of organic matter enter the waterway.
That could happen from the surrounding geography being altered by weather erosion and water that usually went elsewhere is now being diverted into your pond.
You could also take a water test kit and test for phosphate and nitrate at a few points along the stream if the stream is accessible from the surface.
Pictures of the surrounding geography would help here, plus if this has been happening for a few months, maybe review what the rainfall history has been.

 

[Faebinder]

I'm guessing you don't know the number of sticklebacks last year vs. this year? Maybe you have a bunch that birthed and now you are over populated for that filtration and plant levels.

 

[G. Griffiths]

The pool is spring fed i.e. all the water comes from an underground reservoir fed by underground spring(s). the only other water comes from rainwater off the roof of our property (fed into underground pipes to join the underground overflow from the reservoir - also underground).

Stickleback numbers are significantly lower since the occurrence of blanket weed. We used to have visits from the kingfisher on a reguar basis - never see it now, sadly.

Ponside plants incluse wild iris, king cup, and some sort of large watercress. in the pool we have water hawthorn plus a feathery weed that send up pale pink/purple flower spikes - similar to 'ladysmock'. Also reedmace appeared a few years ago and i try to keep that under control and restricted to the centre of the pond.

There is a coarse, pale green/grey, wiry type of weed that grows on the pool bed as well, haven't a clue what that is.

The surrounding geography hasn't changed for generations and no surface water enters our pool.

I guess a few more leaves than usual fell on the pool last autumn from surrounding trees but not significantly more than in previous years.

 

[MitchM]

Is there any information available from your local government on the aquifer that supplies the spring feeding your pond - any construction activity, recently drilled wells?
You mentioned filling in the pond, but won't the spring simply reappear close by?
You may just wind up with a stream flowing overland that is covered in algae.
If this was a gradual increase of algae over the years , I would think that it was simply a matter of increasing organic matter buildup, but you say it has been a sudden appearance.

 

[Meyer Jordan]

Is the size of the springshed known with absolute certainty? Springsheds typically are many square miles in size. Unless the bedrock is fairly cl0se to the surface, this springshed may be quite large. What you are seeing could very well be pollution that entered the springshed many miles away from the springhead and many years ago.
This, of course, does nothing to resolve your problem.
What is the actual size of this pond?

 

[MitchM]

If the home drinking water is from a well, it might be a good idea to have a water quality test done.

 

[moby]

There are very, very few households in the U.K. that use well water as their drinking water, that would be a most exceptional set up. Not to say the OP doesn't, as we obviously won't know for sure till we get a reply, but I'd bet my fish he will be on mains supply.......as are 99.99999% of UK homes.

 

[MitchM]

There are very, very few households in the U.K. that use well water as their drinking water, that would be a most exceptional set up. Not to say the OP doesn't, as we obviously won't know for sure till we get a reply, but I'd bet my fish he will be on mains supply.......as are 99.99999% of UK homes.

Thanks. Good to know.
I don't know much about the infrastructure over there, what about in places like Ireland and Scotland, do the rural properties have wells or does the municipal water supply also reach out to those rural areas?

 

[G. Griffiths]

Haven't used the spring water for domestic purposes for over 30 years now.

 

[moby]

According to a government paper I've just been reading on UK water supply, it confirms that over 99.9% of water is mains in the U.K., you are however correct in assuming in the ROI mains water is less prolific and also in the more remote areas of Scotland where 'private' supplies are used. Private...includes industrial supplies like to breweries and suchlike which also supply homes.
I was I admit, imagining someone with a bucket on a rope precariously leaning over a big hole when I implied it would be unusual!