Another "Golden River"is mentioned in Feet of Clay, a tributary of the Ankh running underneath the Cattle Markets, and therefore that into which well-founded animal anxieties drain concerning the immediate future. This turns out to be much to Wee Mad Arthur's glee and Fred Colon's dismay, as Colon is well and truly dumped in it. Without a paddle.
A third metaphorical Golden River is that of which Harry King is the boss: the River of Urine that would flow abundantly through Ankh-Morpork if it weren't for Harry King and his night soil boys who remove buckets of the stuff from every establishment that doesn't think that stinking of piss is a valuable customer experience. This is the origin of his nickname "King of the Golden River".