I have a 1 acre pond that would get carpeted with algae each year. Last year I drained it and dug it out from 12 to 17 feet deep to try to eliminate the problem. The algae came back this year. The pond is fed from a head wall that runs under the 2 lane state highway I live on, which means I get all the rain runoff from the swales beside the street. My pond overeflows into a pond behind me that is only 4' deep and gets no algae. What can I do to get rid of this problem? I have tried copper sulfate and have to rake the scum out constantly.

Welcome to the forum...

I am sure the experts will be allow shortly to give you advice. Depending on what you're looking for, but the stocking of some tilapia may put a real dent in your FA problem.

Welcome to Pond Boss, thanks for joining in and posting. You could use a pond dye but that has issues as well. Hold on and you'll get better responses.

A few questions first:

1.) Do you do any aeration/mixing (bottom diffuser(s) of the pond?

2.) Do you do any feeding of fish in the pond?

3.) Are the swales upstream fertilized or does the water come additionally from another source like perhaps farm run off or fertilized lawns?

4.) Is there any erosion from the swales?

5.) Is the algae worse in the spring while water temps are relatively cool or is it just as bad all year?

BTW most likely the pond downstream is algae free because your pond's algae is uptaking all the nutrients.

Well, just from your brief description you could pretty much assess depth of your pond is not a factor, in fact by downstream pond depth is not a factor at all. It is not high up on the causes list for FA anyway, but good to rule anything out.

Next, you are either trapping or filtering the problem in your pond, and not letting it get downstream. Residential runoff is notorious for lawn fertilizer runoff. At least you are kind of treating it right by coppering it and raking it out. I have a pond now I tint and rake. It is working pretty well.

It would be nice to know what else is different from the downstream pond and your pond also. Vegetative competition for nutrients could be an issue. Or your pond is a sediment trap for the downstream pond. I personally would need more info, especially on differences between the ponds. And I would realyl pursue the root cause of the algae rather than repetitively treating it.

There are numerous herbicide, chemical and biological solutions, but knowing the cause would really make things easier.

1. I use a fountain whch I pull the water from 1' above the bottom.
2. I do not feed the fish.
3. There would be runoff from lawns and crops along with road washouts.
4. There is no erosion. YThese are typical storm swales.
5. It seems to get worse the warmer it gets.
Thanks

My pond is definately a sediment trap for the pond(s) behind me. I had to dig out 10' of black muck before hitting good dirt. I am concerned with tinting since my pond flows into 2 others behind me and think my money would be washed downstream. Is there nsomething I can do at the exact area the runoff goes through the headwall and into my pond?

There should be enough info in the archives here to keep you busy reading for a short bit!

Everything from identification, control, using dyes, etc. If there's nothing in there that fits your specific application, ask away!

There must be an echo in here!

A diffuser(s) on the bottom would be better for your pond but the fountain pulling that deep should still be good.




O.K. that eliminates feeding as nutrient source.



Bingo there's your problem. The fertilizer that is being used and the sediment washing in is feeding your algae. Be aware it doesn't take much.



O.K. but you are still getting sediments right as evidenced by your silt and muck build up on the bottom?




You're getting plenty of nutrients year around and it's not limited to cold water algae.

Can you build a settling pond above your pond or divert the water around your pond possibly into a makeshift wetland? As mentioned earlier a berm around the pond could do it. Or is there anything in the law that would force the county or state to divert their water away from you pond if you prove it is doing harm or a nuisance?

As long as you are receiving water loaded with phosphorus, nitrogen etc. you will have this problem. Adding chemicals is only treating the symptom and will become less effective over time as you may already know. And of course there's the expense of continually buying chemicals. And you run the risk of sterilizing your pond bottom by repeatedly adding copper products as it is a heavy metal.

A dye would only wash downstream.

Thanks for all the great advice. I do have the room to dig a settling pond, so I think that is my best bet. My excavators have to come back this summer to spread out all the drying muck they removed last year, so they will already be here.

Is much if any of muck pile washing back into pond?

There is not much muck making it's way back to the pond. I contaced my local storm water county official who Is going to do a site visit and give me some reccommendations.