You can go to walmart or gander mntn and for $25.00, there is a large blue book called "Sportsman Connection, Northern Indiana Fishing map Guide"
this book is great, has a topo maps of alot of northern, indiana lakes, rivers and streams. It also tells you what species, popular spots, and local bait shops for some. good luck, havent had much luck at the slough, heard the bite has been early in the day..