UNs IPCC Reports https://www.ipcc.ch/site/assets/uploads/2018/03/Chapter-5-Hydropower-1.pdf See fig 5.15. The outliers are the concern (and yes, it’s pretty much methane)

Edit: I reread the parent comment, the above won’t address what you asked for, but is interesting nonetheless so I’ll leave it

Wait, I’m still catching up. Why would it have been illegal?

Same thing on mastodon, most posts are about Twitter and how they hate it. Really annoying and not the reason I want to use the service