The worst part is that, like so many posts on the Net these days, there is no date stamp, so we have no way of knowing when that was published.
It just so happens that all the frequencies and all the talkgroup numbers line up EXACTLY with their old Project 16 analog trunked system, so how are we to know that these apply to the new P25 system?
They could've published that post years ago and it would look like it's current information.
Also, there are archival sites that would've crawled this page and recorded a snapshot of the page every so often. Google Archives specifically comes to mind. Now they've been Project 16 for years; ever since I can remember scanning them when I started a few years ago. Who knows if it has the original publication date/time of when this went live.
The very presence of this page, existing in whatever space and time, shows that the county is/was willing to place public record information on their site about the system. That's a big thing when it comes to FSS 119 Public Records