The Golden River is a mysterious, possibly supernatural waterfall which exists in a valley in the mountains, not too far from Duckburg.
The subject of the fairy tale The King of the Golden River, this small waterfall periodically becomes golden as gold dust released by hot spring mixes with its waters. According to the fairy tale, a "magic trick" could cause the gold to appear, which was later discovered by Huey, Dewey and Louie Duck to match up with the fact that blocking or digging a small canal between the springs and the waterfall allowed one to control the flow of gold.
The legend also states that only an unselfish person, as judged by the gnome King of the Golden River, may reap the benefits of the waterfall's gold; others who tried would be turned into black stones destined to sit at the bottom of the waterfall forever. No such effects were incurred by Scrooge McDuck when he attempted to collect gold from the River as such, though he did find a number of smooth black stones at the bottom of the waterfall, but things always seemed to work out such that he couldn't keep the gold he collected selfishly — an effect which at first appeared random (though if one account which states the Gnome King was real is to be believed, it may not have been that random after all), but was then consciously engineered by Scrooge's nephews to teach him a lesson about his excessive stinginess.