Replying to Rafting the deshutes

Probably misspelled that. Anyway im going rafting tomorrow morning. Ive done it once two years ago with a MT hood ski camp, but this year the water is a lot higher so its going to be fast and REALLY cold. I heard the average temperature is 45. Its only a 14 mile trip so its not too long. But should i be worried.
 
Im not sure exactly the stretch were doing but they said that its all in mopin.

Oh yea and the reason im worried is that we dont have a guide. But we do have a few people that have done the same trip like 10 times.