You sure its not Ops 7, Ops is not really a Sheriff's Group. It is mainly used for Fire/Ems/Leo local Mutual Aid. Although it has been used for other things. Its been a few years since I was at DCSO and we definitely did not have a OPS17.
It maybe a talk around group(off repeater) added when they switched to the new radios. KE4ZNR would know. I am not sure how active he is here now, but you could send a message he may help you. He works on the Durham System
Yes you would need to talk to KE4ZNR, just talked to one of the communicators and they stated there are other ops channels and they are hardly used. They are probably off repeater but I can't be sure. I do know we had quite a few off repeater channels but I can't remember the names at all. Or if you know his call sign, you can lock out his id when he transmits and see if he transmits on any groups not listed in the db