A rule of thumb - if the pipe is in the DOT maintained ROW, than it is usually a DOT pipe.
CVG has the most elegant solution - call the dot or the county.
Beware, just because a pipe is in one jusisdiction, that does not mean that the other juurisdiction will not also requlate any flows through the pipe.
Here in southwest Florida, if I discharge to an FDOT culvert pipe, I also must meet city and/or county stormwater discharge regs. Ofcourse plus the SWFWMD regs. Clifford H Laubstein
FL Certified PE #58662