When Los Gatos, Monte Sereno or other Santa Clara County residents buy or sell homes here, one of the reports provided by the sellers is the Natural Hazard Report. In it, there’s a statement as to whether or not the subject property is in an area of potential flooding if a dam were to give way.
In Los Gatos, most of the zones marked as potential flooding from dam failure are along the path of the Los Gatos Creek. Lexington is a good sized reservoir, so most of the risk comes from there. Vasona Lake is far smaller, but there are a number of houses just below the dam (which, by the way, sits atop the apparently dormant county mapped Shannon Fault).
Most of us are somewhat “downhill” of a reservoir or two, but not everyone is in an area that would be flooded should the dam burst.
The town of Los Gatos has a flood evacuation map and identifies a number of different zones. This map does not show ALL of the town, but presumably all of the areas at risk from flood from dam failure. To view it, click on on this link: Town of Los Gatos Flood Zones
There are maps for the county, as well. It takes some digging to find these things, and the best one I have found so far is not very easy for seeing the details, but it becomes clear that the largest risk is Anderson Dam, and after that it’s Lexington. Santa Clara County Dam Failure Inundation zones – go to page 95 of 223