I believe DOT is dispatched from it's respective region HQ. For example I live in Wenatchee and Wenatchee is the headquarters for the North Central region and is where the communication center is located. Therefore if you're in Cowlitz county, you're in the southwest DOT region which should be dispatched by Vancouver HQ. DOT is currently running on an old school EF Johnson LTR MultiNet system. There are no scanners that are capable of trunk tracking individual talkgroup. But you can monitor voice traffic on the "status channels" and "voice channels" those channels that sound like open squelch are "status channels" which are basically the "control channels" like you would find on another trunked system. Unlike other trunked systems, the majority of traffic is carried on the "status channel" aka "control channel" basically when voice traffic is carried on the usual "status channel" the "control channel" function of the "status channel" (sub audible data that sounds like open squelch) is moved to the next highest channel (voice channel) at the site for the duration on the traffic, in order to control other radios and handle voice traffic on other talkgroups, then reverts back to the primary "status channel" after traffic has ceased.
The pain in the *** about monitoring MultiNet systems is that you have to be dedicated to listening to it on any particular radio, due to the fact that the "status channel" is constantly transmitting and where you're going to hear the vast majority of traffic.