"Follow the Blood Arroyo to the place where the snake lays its eggs."
The Blood Arroyo is a location that the Man in Black is told to go to by Lawrence's Daughter in his quest to find the The Maze. An arroyo is a dry creek or river bed. By inference we can connect the metaphor "blood arroyo" to the "red river" landscape feature mentioned by Sizemore in his narrative presentation.
The Man in Black brings Lawrence home to Las Mudas. Lawrence's young daughter eventually gives the Man in Black a clue about the The Maze. She tells him: "Follow the blood arroyo to the place where the snake lays its eggs."
The Man in Black and Lawrence are in a a blood arroyo (dry creek bed), and the Man in Black is killing snakes and cutting them open. He says none of them are of the egg-laying variety. They see a woman bathing in a river. She has a snake tattooed on her exposed torso, neck and face. The Man in Black realizes she is who Lawrence's Daughter meant by "the snake". He meets her and asks her if she would be willing to answer a question about her tattoo. She states that she will tell him what she knows, but first he must rescue Hector Escaton from Los Diablos Prison.