Some links to look at. A pretty location to go fishing/camping. As with most reservoirs/lakes, especially ones that drop off quickly along the shoreline, you best off trolling close to shore (less than 20' depth), working the points and inlets and if casting from shore with lures cast parallel to shore. Try letting your lure sink some before beginning your retrieve. A bubble and fly might be a good bet in the evening or early morning.

http://wdfw.wa.gov/fishing/vacation/ross_lake.html

http://wdfw.wa.gov/fishing/washington/122/