[![enter image description here][1]][1]

From the Chart Supplement for both airports it seems both are not attended Mon-Fri 10 AM to 4 PM.

And for 1O5, it's likely the service in on-demand by calling up ahead.

    1O5: Unattended
    SIY: Attended Sun–Fri 1600–0100Z‡

I got the chart supplement for both airports from [skyvector.com][2].


  [1]: https://i.sstatic.net/t0663.png
  [2]: https://skyvector.com/airport/1O5/Montague-Yreka-Rohrer-Field-Airport