Isis
The name of Egyptian's goddess of river Nile is Anuket.
Heqet was married to the god Khnum. That made sense to the Egyptians since Heqet was the goddess of human and Nile fertility and childbirth, and Khnum was the god of the source of the Nile and the 'creator of babies'. Khnum was however also sometimes romantically connected to the goddess Satet, yet another Nile deity.
The hieroglyphs explain them that when there was flooding of Nile it helped in agriculture that let is to be worshiped as the river goddess.
She controlled the flooding of the Nile River.
The ancient Egyptian deity that was considered the goddess of the Nile River, the child of Satis, and among the Elephantine triad of deities is Anuket.
Satet goddess of the the inundation of the Nile is depicted as a woman wearing a star on her head and carrying water jars.
The role of Anuket is described as being the water goddess of the Nile cataracts and the fields.
In the Greek beliefs, it was Nilus. In the Egyptian belief system, is was Anuket, who was a Goddess.
The Nile River fits your description. It was so important to the Ancient Egyptians that it became a part of their Religious beliefs. They called the Goddess of the Nile, Anuket.
Hapy was a God. The God of inundation (Flooding) of the Nile.
According to my research, Anuket is the goddess you are searching for.
Isis is the Nile Goddess that crossword puzzles ask for.