Knowing how many spots each District gets is, in many cases, not very useful information.

The real question is: How is your WIAA District going to distribute their allocation?

This could vary.

You may have a case where a WIAA district holds two league championships to establish 8 of their hypothetical 9 entries. It could be top 4 placers from each of two league tournaments.

That leaves one more spot. Then the District could hold an additional tournament the next week, the winner of that tournament gets the last spot and goes to the Dome.

I don't think there is a Rosetta stone for this readily available and posted online.