u/Familiar-Bowl3591

I don’t have much info and can’t remember a lot - but I read this book around 2015 or before. I remember in the very beginning of the book, a young girl goes missing and is found in a ditch/stream in town. Another young girl investigates this disappearance throughout the book. It is a YA book, has some introspective themes and uncovering of a bigger problem in the town. Any help would be appreciated!