welcome to PB john. FWIW, i have some comments about willows on a dam.

willows consume huge amounts of water. willow roots are shallow. willows do not have large invasive tap roots. i had about a dozen 40 ft tall willows on my dam (inside face). i used a large trackhoe with a thumb and plucked them out whole. the roots came out like a big round plate not more than a couple feet deep. used a dozer to re-groom dam face.

if you have other species, particularly oaks or cedars, then it is much more possible you could leave root rotted pathways into yer dam, i wouldnt be concerned with removing the willows from that point of view. you will decrease the amount of organic crap going in pond, but you will also lose shade and habitat for birds and insects........theres always trade-offs and it depends on yer goals.

pics of 13-15lb bass? yes, please do post.

GSF are people too!