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I remember that the two classmates he pulled into the water, a girl and a boy, were dating. I think the teen had a crush on the girl, but I might be wrong. I think the boy was kind of a punk or had a bad reputation or something. I remember there was some kind of a large rock or plateau that teenagers liked to swim out to, I feel like they had a certain name for this rock but I can't remember what it was. The teen swam up behind the rock and I think he was insulting the boy and grabbed the girls leg, but I could be wrong. I think the girl slipped because the teen grabbed her and the boy tried to hold on to her and that's why he fell too. I think they blamed what happened on the boy, a lady saw what happened from the front side of the rock and to her the girl screaming "No! Stop!" while the boy was hanging on to her looked like him trying to take her top off. I also remember them holding a memorial for the teens out in front of the rock they fell off of. I think they lit candles on little boats or something and sent them out in the water. Does anyone have any idea what book I'm talking about?
You were right- the book is called "Blackwater," and is by Eve Bunting. http://books.google.com/books/about/Blackwater.html?id=o2mR-YUD4roC

I remember a lot of details but can't seem to find this book. It was about this teen who accidentally pulls two of his classmates into the water while trying to play a joke on them or something. They get swept away by the strong river current and he jumps in to try and save them. I think he is knocked out in the process and his cousin tells everyone the teen is a hero even though the cousin knows it was the teens fault the classmates fell in. I remember the cousin was visiting or had just moved in or something and was a real brat. He was trying to get on the teens good side so I think that is why he told everyone the teen was a hero when he knew better. The bodies of his classmates are found later that week and the local media starts hyping the teen up for having tried to save them. The struggles with deciding whether to just accept the attention or set everyone straight. Someone, I think it turns out to be the girl who lives next door who saw what really happened through binoculars, starts sending him letters telling him to confess. Eventually he does confess and I think the book ends right after he comes to this decision. I think the book was aimed at young teens and I really want to say the title was something along the lines of Dark Water or Black Water, though I could just be making that up. If anyone knows this book please tell me because it's annoying to remember so many details but still not be able to find it.