What kind of structure/cover does your lake have? My home lake is an old reservoir as well. The old creek channels are silted in, and break lines are pretty much non existent, more like a gradual slope from shallow flats to slightly deeper water where the channels used to be. Those areas hold lots of fish in the Fall and winter months, especially where there is some really pronounced structure, ie. bridges, main lake points, docks, etc. Then they scatter to the millions of Cypress trees in the Spring and Summer months.