Consider the big picture here. What came first the chicken or the egg. My concern would be that a primary cause of your stunted BG pond is its tendency to have large winter kills. That may be a major factor in its cycle of going from stunted BG with few LMB to where it was just before this event (stunted BG with a fair # of good LMB). Now it is starting the cycle over.

If that is not consistent with your goals then you will have to deal with the winter kill propensity (determine why [to cold or low DO or both]and how to stop or limit it).