I suspect a willow loosing a few roots won't be too harmed, and every hunk of root yanked out shall probably grow somewhere downstream. LOL. There are various willows suitable for hedging you know. Arctic willow coming to mind. If you have the room, just let them rip without shearing, they'll be tall enough for privacy and quite hardy. I have goat willow planted in a situation much like your's. It's a bog area where one of my springs runs off and very near drainage ditches maintained by the county. It is also about the same proximity from a septic field and I have had no issues whatsoever from it and it's been there years. It's a smallish, but very full tree and the roots are plenty far away from the field at that distance.

There appears to be some confusion here. The dappled willow is normally a weak-wooded (yet vigorous) bush. However, this sort of bush can be top-grafted onto a standard (standard=trunk) of some stronger sort of willow to make a TREE FORM willow. If it is "tree form" it is 99% certain to have been grafted--check where the "bushy" part meets the trunk to be certain. Because the tree form is grafted, any growth from the trunk of a tree-form dappled willow will not be the same kind of willow as the top growth, and therefore, should be (must be) cut off. The pruning of a standard (grafted) dappled willow tree involves cutting the TOP BRANCHES (the grafted-on part) back by 1/3 or even 1/2 every spring, and removing unsightly sprigs at any time. If you saw the graft off the trunk, you will get either a dead trunk OR the trunk will sprout into whatever kind of willow was used for the trunk. As to the height of the dappled willow TREE FORM, once the graft has been put onto the new trunk, the trunk grows very slowly--for all intents and purposes, the height you buy is pretty much the height it will stay, except that the top bushy part will get to be a bigger and bigger tuft every year.

Well so far I've had "experts" tell me the tree will likely die if I chop it off,... That it won't die if I do, (In fact that this is done purposely to make telephone poles etc) To cut it to the ground or get rid of the pool but also not to cut it to the ground. That it will look terrible if I top it, and I've seen actual pictures that dispute that. That it will get massive and top heavy and be more of a problem, but also that it wont ever get big again or be a problem and that it can be trimmed easier (and cheaper) if it does start getting too big.... That it was likely planted there to soak up excess water but then a dispute that it likes water but that there wont be excess water if I get it cut down, So I'm gonna wing it. I'm not cutting it to the ground. And I'm not letting it get any bigger either. Any bigger and if it's true that they only last 60 years, it will fall on my house and likely kill me. If I chop it off, I think it will look bad for one season and then look fine again. I think that it wont get as massive and if it starts to I will get it cut back cheaply before it becomes a monster. And... Ive read that by cutting it back, not only is it not detrimental to the tree, but it keeps the tree "young" and theoretically, if it was continued to be topped forever, the tree would actually never die. Thanks for the advice everyone but I gotta do what I gotta do. Tree experts are like doctors. You can always find one to disagree with the diagnoses or the solution.

Those are burls and can be very common with willows. Burls are a type of growth where the wood grain forms in a deformed manner and typically show as a rounded, knobby growth on the trunk or limbs. Causes are varied but they are not generally know to cause damage to the tree they appear on. Large burls tend to be very sought after by woodworkers for the stunning patterns they exhibit. Just an FYI but willows are known to be prone to a whole slew of disease and insect problems as well as weak wood that can cause limb drop or splitting. The decline you are seeing could be a reflection of one or more of those problem as well as just a sign of old age.