looks like this may be a earthen dam, doesnt show up in official CA dam inventory but never the less if confirmed could be good to add dam feature

there is a fire station located here, name is not known though

suggest merging all the individual areas of this park into one relation

I think this ditch is really a underground water pipeline, if anyone knows please update tags

some refinement to represent the service road here is needed here to make it work without overlapping the reservoir water area

I doubt this school still exists here, suggest removing or tagging as "historic:amenity" if so

there seems to be 2 campground pois with the same name here, suggest consolidating into one poi or adding a area for it. It could also be that these are camp pitches instead of campgrounds which in that case should be updated to reflect that.

ferry line here could be updated to be more specific to be helpful if more information is known on operator, whether there is a fee, and if its only pedestrian or not. Also if the crossing duration is known that would be good to add as well. osm.org/way/10570115

some building footprints in this area should be split into separate structures as some outlines contain more than one building structure, a building should be an independent structure...