First guess would be to check the Lake Metropark UHF frequencies: 453.3/458.3, 453.95/458.95, and 453.9875/458.9875. I could see where a cross band repeater would be useful when the rangers need to coordinate with the other park divisions that don't have MARCS radios. 453.3 is the wide area repeater in Concord, 453.95 is Farm Park ops and 453.9875 is Erie Shores GC.
The other possibility is the 8CALL/8TAC mutual aid repeaters. A while back Lake County deployed a few repeaters at low profile fixed sites, mostly in the Kirtland area where trunked system coverage was poor. These repeaters were permanently patched to trunked groups such as Kirtland PD and Kirtland FD. I'm not sure if these fill in repeaters still exist, with the migration to MARCS-IP and the ability of users to roam to adjacent sites they may not be needed anymore. While technically not a cross band repeater, I wouldn't expect an end user to know the difference.