Vince & Jeff--Don't believe Google Maps--Eureka Lodge is actually a few miles on up the road in of all places, Eureka. So don't look for Eureka Lodge to pin point the Silver Lake Mill. The road from Eureka to Animas Forks is either on the SN grade or very close all the way between these 2 points.
Silver Lake Mill can be accessed from the top of the mill site with a fairly short walk from the county road that takes off from the Arastra Gulch road--there are maybe 20 homes on the hillside above the mill and on onto Silverton. Both Silver Lake Mill and the Waldheim mansion site can be accessed this way and fortunately most people have never figured this out.