What does it mean when Norman says, "I am haunted by waters" in A River Runs Through It?

This is the final sentence of the book. The author uses this memoir to recount how important the activity of fly fishing was to him, his brother Paul, and his father. In fact, Maclean opens the book with the line,

In our family, there was no clear line between religion and fly fishing.

The Macleans lived in Montana, and they fished as often as they could while they simultaneously dealt with the usual activities of...

This is the final sentence of the book. The author uses this memoir to recount how important the activity of fly fishing was to him, his brother Paul, and his father. In fact, Maclean opens the book with the line,

In our family, there was no clear line between religion and fly fishing.

The Macleans lived in Montana, and they fished as often as they could while they simultaneously dealt with the usual activities of daily life. Even though this story is true, we can see the recurring image of the river as a metaphor for the passage of time and for the course of a human life. Just as water hurries around rocks and sunken tree trunks, so do people meet and deal with challenges that they encounter along their way. There is no way to stop the progress. The river keeps flowing, just as the pages of the calendar keep turning.

A little past the middle of the book, the author references this relationship when he writes:

As the heat mirages on the river in front of me danced with and through each other, I could feel patterns from my own life joining with them. It was here, while waiting for my brother, that I started this story, although, of course, at the time I did not know that stories are often more like rivers than books. But I knew a story had begun, perhaps long ago near the sound of water. And I sensed that ahead I would meet something that would never erode so there would be a sharp turn, deep circles, a deposit, and quietness.

That something is this book. By the time Norman shares these memories with us, Paul has already been murdered under unusual circumstances. This story is therefore a tribute to his fallen brother, his fellow fly fisherman. Even though one man has been lost, the river still runs; the water still flows. Time passes. Norman can still remember the times they fished together; he can go back to those places to fish again and to mourn the loss of Paul. The lives of the Macleans and the water of the river were always intertwined. Norman cannot change what happened to Paul. He can only remember, as he continues to go with the flow.