The Largemouths are not likely to be found in open water so look for structure of some sort. The Smallmouths are often found where there is some exposed bedrock of some kind. A medium sink tip works well. Work along the edges of weed beds and rocks with bait fish patterns, wooly buggers, muddlers, etc. Vary speed of retrieve and depth.
Poppers work good in the spring.
Purple San Juan Worms work great for smallmouths. This river is like the other Central Valley Rivers. It is making a modest comeback after years of neglect and poor river management practices. It is not a blue ribbon stream by any means, but if treated with respect and care, it has the potential of becoming a very valuable recreational resource in the future. During the summer, there are many rafting companies that take advantage of this fragile resource.