Pictures below are of my sediment pond with a terrible FA problem. I treated one time around the edge with Cutrine liquid and it knocked it back a couple weeks (when the FA was mostly noticeable around the 3' perimeter). It was getting to be summer and hot weather so I thought I would be in the clear as the water got hotter. Nope.
First picture is the pond as it was a couple weeks ago. I then raked the FA off around the edge that I could reach with my rake. This helped as far as the fish go as once I had clear water around the edge I could see the fish utilize this new open water.
Ran out of time (and it was horribly hot to be raking FA out of the pond) and left for a couple weeks on vacation. Got back and it looks like I had done nothing. Just a small area around the aeration plume of open water and several small other openings.
Raked some more tonight to open up the edges again.
I do not really care too much about this pond being covered. It is after all a sediment pond. I am raising some LMB fingerlings in it to later transfer to my main pond (in the back ground in some of the pictures). My main concern is if it comes a big rain event and water goes over the emergency overflow (which it will if it comes a 3" rain pretty quickly) all the FA will end up in my main pond where all the water flows to.
Some background. This sediment pond had a massive fish kill earlier due to some very fine dusty chicken litter (manure and wood shavings) applied to the adjacent field and a sudden unexpected downpour rain that washed this fine dusty litter into this sediment pond. It was a near total kill of the remaining fish that were not transferred to my main pond (strong wind blew the gasping fish to one end where I dip netted most out and transferred to main pond). A small number of 1 to 1.5" fish did survive (including GSF naturally). The sediment pond did its job. Some of the excess nutrients did flow through to my main pond (3 acres) but the majority settled out in this 1/10th acre pond. So the nutrient load in it was tremendous with all the organic fertilizer that has high levels of N, P and K.
The first year the water primrose that had started around the edge thrived and was the darkest green color I have ever seen water primrose. It extended out about 3-4' nearly all around the pond. I actually liked this as I thought it would be a good use of the excess nutrients. I drug some of it out at the end of the first year (the next year after the fish kill). So I thought it would be back this year. But instead this year the FA overcame the water primrose and essentially chocked it out.
I would have much rather had the primrose back instead of this FA. Interesting how the pond has utilized the excess nutrients in two completely different ways in the two years following the fish kill.
When raking the FA out of the pond I figured we would have a really windy day that would compress it to one side of the pond making it easier to remove. Have not had the windy day at least to date when I was at home. If the FA is still touching the bottom the wind will not blow it very well. If you get it "broke loose" a good wind really compresses it and makes it much easier to remove.
I'm sure no expert but this is from my experience. I think the FA grows in deeper water too and when some breaks loose and floats to the top, the mats tend to drift around the edge of the pond. I doubt you impacted that much only treating out 3 ft. I had the same severe problem about 3 years ago nearly covering my pond. I divided up the pond into 3 sections and treated each section at 2 week intervals. Since then I have used pond dye and nearly no FA at all but I do see small patches of it still growing next to the shore.
