That’s something I heard from someone restocking fish. So, it might be an artifact of US dams being over 50 years old on average, but I assume that generally holds true globally.
As to peak methane production, yea that seems reasonable. Though a great many dams didn’t cover forests, so the extremes aren’t representative of the average.
I am not disagreeing with that, just saying the weight of twigs deposited by rivers behind dams is significantly more than the weight of trees that where drowned by the dam formation. Visually trees are very striking, but chemically even tiny fragments of leaves are important.
As to peak methane production, yea that seems reasonable. Though a great many dams didn’t cover forests, so the extremes aren’t representative of the average.