I think a split is coming soon for WF with 33 girls on the JV and Varsity this year and 13 at 15U. In the 40's with their 12U teams so a few years likely.
I don't think they are quite at the numbers level that the Bismarck girls are. Roughly 50 between the two Varsity girls teams in Bismarck right now amongst St. Mary's, Century, BHS, Legacy, and Shiloh. They have 15U/14U with almost 30 girls collectively.
*Edit, I see that the 12U levels at Bismarck are a tad low for feeding two teams in the future. Unless they move girls up to the 14U that won't get much out of playing 12U.