If it was a bridge in downtown, he was on the sacramento river. This river has been dredged for sediment removal for 100+ years as it is a major shipping lane. I have also prospected arden park at watt ave, flyspeck...the problem is there are no alluvial sources of gold in sac valley. Any gold in the american or sac river is float brought downstream from the foothills. There are also a ton of dams and power houses on these water ways, and that impedes the downstream movement of gold. Also, most parks in sac are pans and hands only, I got yelled at for using a shovel there once.
I heard there is gold in the feather river, but you have to go 15 or 20 miles upstream from the confluence with the sac river. The consumnes has less dams on it, I have had half gram days on it out by slough house road and rancho murrietta. I have run pans below folsom dam amd got micro fines, so I recomend auburn state rec area as the lowest point to start on north fork american.
The middle fork american in forresthill divide is pretty claimed up, amd I havent had the best luck working un claimed areas. South fork american is similar, pretty claimed up but have had a lot better luck in unclaimed areas, downstream from chili bar, even panned some flakes from the cobble fields on other side of bridge in coloma.
Bear river is good for fines and mercury, not much else. Greenhorn creek runs through some old hydraulic pits before it feeds the bear, look for red dog- you bet diggins on google. Dog bar road on bear river has better gold than the campground.
That about does it for my knowledge of sac valley gold, there aint a whole lot! If anyone disagrees, please respond. I love learning new things
