I see, that makes a bit more sense. Boy, pulling the cattails up vertically is tough. That is the strength of the plant. Side cutting just below the surface to right above the rhizome is pretty easy with the right tool. Old dead growth is the hard part, and you are on top of that. I would imagine you have and upwind source of seeds blowing in. If that is the case you may have a neverending battle for control of the shoreline new growth. You might have luck spraying a preemergent on the shoreline at low water also.
If you are establishing a new high water mark and are submerging old terrestial growth, that is an algae maker for sure. But it looks to be you are doing everything I would do, early eradication, no chemicals, removal of material. After this algae bloom you might want to sit back and see if that depleted some of the nutrients. Also with a new pond I would probably introduce some beneficial bacteria. Get in front of the nutrients and muck/sludge. I would avoid chemicals and stay the course if the labor does not bother you. The keys are early removal and staying on top of it. Good job.
