Land Office Map of the Central Pacific Railroad and the Dutch Flat Donner Lake Wagon Road, detail,
Bureau of Land Management, Sacramento, California, archives of old Land Office Records.
(Dana Scanlon reports that these California Land Office Maps include a tremenous amount of information.  The maps from Auburn to Donner area include the CPRR.  The surveys were too early, or were part of Land Grants between Sacramento and Auburn.  The surveys were also too early between Donner and State Line.  One of the survey notes mentions contact with several groups of CPRR surveyors east of Donner Pass.)
Courtesy of Dana Scanlon.
See enlarged map below.