mm wrote:
A 16" diameter tree fell across a stream and a neighbor doesn't like
it because leaves, sticks, etc. and some plastic bottles, like retail
water bottles, and other soft plastic and a few aluminimum cans pile
up behind the log, and she says it smells some times.

Do you really want to (have to) cut down that tree? In many places you
won't have any obligation to do anything if it fell because of natural
causes.

If you have to, do yourself a big favor and hire someone to do it.
Felling trees is a dangerous biz by itself that gets much more dangerous
if you have to work standing with unsafe footing in a stream.

No offense, but you don't seem to have much experience working with a
chainsaw which adds the third risk factor to the job. Too many,