Best action is from midday on near the dam area. Midge hatch is sporadic, but may have a few trout working the dries on warmer days. Streamers and mayfly nymphs fished on a Stillwater line are your best bet. Some of the edges of the lake are frozen. McCumber is located just east of Shingletown on the way to Manzanita Lake.
Fishing is fair, and can be good if flows stabilize.
Best action is from midmorning on. Access is along Chalk Bluff Rd. The canyon section above the Reservoir is also good - it requires a hike, but you will get away form crowds. Blown out - water is spilling over the Glory Hole at Lake Berryessa. Does not look like the water will drop for the next week or two - at least.