The Bay County Library System (BCLS), is a public library system serving Bay County, Michigan.

In 2000, Bay County voters approved a millage increase and bond issue to support capital improvements to the system, including new buildings for the Bay City and Pinconning branches and additions and renovations to the Auburn, Sage, and Southside branches[4] Renovations to the Auburn and Sage branches were completed in the winter and spring of 2004, respectively.

[6] In December 2005 the Bay City Branch was replaced by the new Alice and Jack Wirt Public Library.

[8] As a result, the Bay County Library Board voted to close the South Side and Sage branch libraries, suspend Bookmobile service, and open the Auburn, Pinconning, and Wirt branches for restricted hours.

[9] Renovations to the South Side Branch are currently on hold pending resolution of the library's current operating funding situation.