Page 19 in the book "DOWNIEVILLE Gold Town on the Yuba" (volume 1 of the James J. Sinnott's History of Sierra County series of books) states that "T.M. Ramsdell" was elected county treasurer in the June 1852 election. He and the others elected were the first Sierra County office holders. His political party was Democrat. It is an out-of-print book. But you can find it in some libraries and for sale as used.

I am slowly creating a complete surname index for that book and posting it a few pages at a time at the below URL. I am willing to do look-ups in the book. So you may want to check that page from time to time. I probably won't finish it until the end of this year.
http://cagenweb.com/sierra/Ref_books/SinnottV1.html

Hope that is helpful,
Rick Hanson
CAGenWeb County Coordinator for Sierra County (http://cagenweb.com/sierra/)
RichardLHanson@gmail.com (checked daily)
or sierra@cagenweb.com (checked weekly)