Yeah, I know, I copied-and-pasted the title "as is".
I can't find a list of episodes, but I'd guess it's from early-to-mid 1980s, since Bill does look a bit older than the earliest Picture Pages from 1974, and I don't really remember "environment" being a word used in children's programming in the 1970s. (I'm not saying there weren't environmental themes in American children's programming dating back to at least the "Willie Wimple" cartoon shorts from 1972, but "environment" was too big a word for kids shows back then.)