There doesn't appear to be many major agencies in Scioto Co using MARCS except for the OSP, ODNR, and the "patch to Portsmouth PD":
With that said, you may hear more if you monitor more sites. If you are monitoring a single MARCS site, you aren't guaranteed to hear all of the MARCS traffic in your area.
Depending upon how close you are to the sites below, and how well you receive these sites, it may or may not benefit you to add more than one MARCS site in your scanner and scan multiple ones for activity.
Also - make sure you run that system in ID SEARCH mode and turn on I-CALL so that you are sure to hear any/all traffic that is being broadcast off of the towers you are listening to.
Sites that may be nearby you:
6F16-022 W PORTSMOUTH (SCIOTO)
6F16-023 STOUT (SCIOTO)
6F16-025 GREENUP, KY (GREENUP)
6F16-026 IRONTON (LAWRENCE)
6F16-027 HUNTINGTON WV (CABELL)
6F16-029 WHEELERSBURG (LAWRENCE)
Mike