Looking for a book: Young woman comes back to her hometown with secret and looks into who could be her father. Small town. Lake. Jogging club.

I likely would have read this somewhere between 2005-2010, though I don't know if it was new at the time. I can remember it was about this girl who I think came home to stay with her mom from a failed attempt at college surrounded my mystery that she wouldn't talk about. If memory serves, she came home pregnant. It was a bit about finding herself and who she is and solving her own mystery of who her father could be because her mom never said. It was a very small town with a lake that I think had rumors of a monster (but this wasn't really a thriller). She jogs in the morning and there is a group of older people who also jog too. I think the father ended up being someone who jogged. Can't remember if the guy was still alive or not. The girl might have worked at a library while she was searching for her dad or I might be remembering part of another book.

Any help is greatly appreciated!