Online GPS Lake Maps with contours?

Hey does anyone know of a site where you can view lake contour maps that also has the GPS coordinates on it? I know Navionics has a good map site that allows you to view all the contours but it doesn't allow you to mouse over something and view the GPS coordinates. For those of you that want to be able to view a contour map you can do it it at.

http://www.navionics.com/en/webapp

The show very good details of most lakes I just need something for GPS coordinates. I bought a Lowrance Mark 4DSI last year but it doesn't include the contour lines for Milford so I would like to get the GPS points so I can put in some points of interest to me.