Big Bear is very fishable during the winter, just be prepared for cold water and cold weather....Use full sinking line since most fish will be holding on the bottom. Use a float tube, pontoon or Kayak and just strip WB or other types of streamers along the bottom. Black or Olive WB seem to work very well. You could launch anywhere along the road where you have access to parking and the lake. For the most part I would launch by the dam, but you could also launch by the observatory. I think you might also need a permit for your water craft, although I have never seen that enforced and I have never been cited for not having one
Hope anyone reading this finds it helpful 
