Again, Poe wants us to see that the whole world is sad in this poem. Even the water in the lakes is sad. To drive the point home, he repeats the word, telling us twice in a row about the cold, sad water. After a point, we feel like we are sort of marinating in the unhappiness of the speaker, and that's exactly the point. This is a poem about a strange place, for sure, but it's also about a mood, about the way that our feelings can change the way we see the world. This is a kind of crazy poem, but at the same time it paints a moving picture of what it's like to be really unhappy.