What kind of demon is Heishui River?

In the sixth episode of The Journey to the West, Jilong, the evil spirit in Heishui River is Jilong, the nephew of the West Sea Dragon King. He disobeyed the discipline and the advice of the Dragon King, and almost ate the Tang Priest. Heishui River, a first-class tributary of the left bank of Jinsha River, the mainstream of the upper reaches of the Yangtze River, originated from Maguoliangzi, Zhaojue County, Liangshan Yi Autonomous Prefecture, Sichuan Province. There is a big tributary on the right bank of the upper reaches of Heishui River, which flows into harmony.