Still reeling from the shock that the style wasn't called "Sinister Suers", naturally 😉!

I suspect green became the default sewer-water option as an easy way to differentiate it from the blue "ordinary" water which didn't involve anything too "realistic" (given blue as normal water isn't realistic either, of course).

And are we calling these the Sue-ers now 😉😁!

Misread that initially, and thought you'd typed "violet minotaur" - the colour scheme, as we've explored above, is everything! (Could be your purple patch in this case, Sue 😉.)

Delightful! 🌈💩

How many hexes is that? 😉