Some if not most of those plants are just slowly take care of them, as you go. Mechanical or manual is labor intensive but best. But that duckweed can explode on you, cover the pond and leave a sun blocking mat, killing everything below it. Tilipia are great for it, if you want to go that route. One of the keys to duckweed is get it early before it has a chance to take over. Plants tend to battle each other for growing space, nutrients and sunlight. Surface plants can kill everything below them. I have a pond where it is battle of the invasives, creeping water primrose vs parrotfeather. Not much beats them. But in your case I think most of your plants are natural and regional. I try to leave a little of everything and just keep it in check as I go. Cattails I like 5% of less of shoreline. The shoreline grasses should not be too much of a nuisance. And you want a algae bloom of some sort. A little effort and you can have a very nice pond.
