Carolyn Keene 
Fishing for Clues [EPUB ebook] 

Something fishy is going on in River heights and Nancy Drew is on the case!Ned’s mother falls sick after a fancy fish dinner and Nancy suspects it’s more than a simple case of food poisoning. Some investigating reveals that the river is polluted and it’s poisoning the local fish, but the Health Department’s reports say the river is clean. Could the local paper plant be in cahoots with the mayor’s office?