In our area it is the water and sewer commission. They are currently surveying installations for compliance and came into our place at 4pm on Friday several weeks ago and wanted to see the inside of our undersink trap. I told them no way was I opening the trap on a Friday afternoon and promised to invite them out to clean it next time I needed it done. I expected to hear something from them but never did.
real funny story here too! about 3 months ago a lady walks into my shop demanding that I open my grease trap so that she can inspect it and make sure it is working properly. She brought in the copy of the code that the clearly states that I must make my grease trap available for inspection. I told her there it is and she in a very hard tone demanded I open it, which I said nope. If you want it open you can go right ahead because it says I have to make it available to you it doesn’t state I have to do your job…she stormed out never heard back from her…
and to answer your question all of the above can give you the right answer I would check with the health dept myself.