This what I know about the quote attributed to D. O. Mills.
It shows up in the 1933 edition of W. A. Chalfant's book
The Story of Inyo. But it is not in the smaller 1922 edition of the book. Chalfant was a long-time newspaper editor and publisher in Bishop in the Owens Valley. I suspect that Chalfant book is the source to all of the later quotations.
Dick Datin once told me that he had tried to find a contemporary reference to the line and he was unable to find it. He did find that Lord Baker, the head of the Borax company, said that the Borax company's Tonopah & Tidewater had been built 150 years too soon or 150 miles too long; that comes from the first or second decade of the 20th century.
Chalfant was in the Valley at the time when the C&C was completed so maybe he remembered something that was not written down. Or he may created the quotation himself.
My own reading of newspaper micofilms shows that there was a trip by Mills shortly after the completion of the line all the way into the Owens Valley and down to the lake and Keeler (then named Hawley on the railroad). The newspaper in Independence (not Chalfant) does mention the trip and adds the statement that Mills and party should travel to the west side of the valley and see the agricultural activity there. Interesting is that the Hawthorne, Nevada, paper did not seem to mention the trip by Mills.
D.O. Mills or H. M. Yerington may have made or written such a comment at a later date. The Yerington letter books may provide a clue.
Brian Norden
a long time student of the Carson & Colorado / SP narrow gauge