For a map of the lake go to Walmart, they have a book that has topo maps of all the lakes in the state of Iowa. About $20 and well worth the money. They even have all the small public ponds.
FYI this winter the oxygen level was down to 1. This was tested just out from the boat ramp on the south side by the aerators. We are expecting a fish kill.
As for where to start on Silver Lake try the jetty on the south side of the lake. In a couple of weeks you will have to fight people off to catch the yellow bellies (bullheads). As for structure there basically is none. It is a kidney bean shaped lake that is like a bowl. 6' deep max most is about 4'. As for fish species, bullheads, perch (mostly small sorting required), a few northern.
Try if you want, I don't know if there is anything left alive.
Post if you catch anything.