young girl, summer fishing, her or friend is sick (cancer maybe?)

[Jess]

I read this a LONG time ago but it is a young adult book I think. Every summer they go to a lake to go fishing, and there is allegedly a monstrous fish in the lake that has not been caught in years and is suspected to be a legend. I'm pretty sure the young girl ends up seeing it sometime in the book, and then knows it's for real. Either her or her friend (a boy) has to go to the hospital because they are sick. Possibly cancer?

Any help would be appreciated. I read this a long time ago and it has always bugged me that I don't remember it. Thank you!

[Lobstergirl, au gratin]

Jess, are you still looking for this or did you find it?

[Lobstergirl, au gratin]

Lobstergirl wrote: "Jess, are you still looking for this or did you find it?"

No response in 2 years. Moving to Abandoned.