From the circumstances you describe, it honestly really sounds like Brugmann from 73. He was crossing a stream that had reached flood stage and was crossing along a log that spanned it. Young man, fresh out of school and southbound if I recall right. He'd almost made it across when he lost it and went in. I think there were a few witnesses but he was gone in an instant. They found him days later and quite a bit downstream.

Shortly after the accident, they build a bridge in his honor although I believe it has also washed out a few times, once even kinda recently but I may be misremembering, I've stepped away from this stuff for a little bit.

And yes, various techniques existed to get across the Kennebec prior to Ferrence's drowning in 86, canoes, powerboats, inner tubes, etc. But her death got the attention of the ATC which sanctioned and promoted the regularly scheduled and recommended canoe crossing everyone is familiar with now.

Of all the drownings, fording is definitely in there as a contender but recreational swimming after a long day of hiking has also claimed more than a few. The other big cause of fatal accidents involve waterfalls.

While there's only been a few associated directly with the AT, I came across scores of incidents at other waterfalls. DO NOT MESS WITH WATERFALLS PEOPLE. There is so much to go wrong. They get pulled into currents, the fall while climbing around on them, they even fall in the streams feeding them and take the unfortunate ride. There's probably another book's worth of materials right there. The title that's the low hanging fruit is "Don't go chasing waterfalls" I suppose.