We call them "proglacial lakes." There are a couple of different kinds of proglacial lakes, in this case, they might also be called glacial moat lakes.

When a big ice sheet melts, isostatic rebound of the crust is delayed, resulting in a moat around the retreating ice. Drainage is poorly defined, constantly changing, or may not exist at all. In this case, some of these lakes were part of a much larger lake known as Lake Agassiz, named after the famous founding glaciologist.

As for the seemingly regular spacing, I'm not sure why that might be. The first step would be to apply some geographic statistics to the bodies of water and see if there is a true periodicity verses they just look regularly spaced.

I remember when I was taking a glaciology class in grad school under a rather well published glaciologist, when we were discussing the retreat of the Laurentian Ice Sheet, I noted that the Great Lakes were located at the contact between the Precambrian rocks of the Canadian Shield and the much younger sedimentary layers. He responded with a raised eyebrow, a "hmmm", then a suggestion that that would make an interesting study. If you look at a geologic map of Canada, this same relationship holds for the other big water bodies. So I believe there is something about this contact between hard and soft rocks localizing the proglacial lakes, possibly due to the original scouring at the base of the ice sheet coupled with isostatic depression.