I didn’t say you did, you linked to a local magazine website for Lake Superior which puffs Lake Superior. Link to peer reviewed academic papers covering both lakes if you want to prove your point. Normally Wikipedia settles things, but in this case it doesn’t as it is silent, so it is still appears to be a matter of academic debate.
in Dresdenverse the ley lines have been important to the plot for Dead Beat, Changes and Cold Days so their disruption or re-alignment are key to destroying Demonreach. The ley lines locally erupt from Demonreach and appear to have been created by the Merlin. They link into the local network and presumably provide an anchor/ grounding for it. Cutting that anchor would leave Demonreach vulnerable. Only a Dragon could do that - it was intimated in Peace Talks/Battle Ground. I bet the Dragons originally created the Ley line network either by accident or deliberation.
This makes me wonder about Sirriothrax and the two different versions we get of his death. The swords are powerful enough to kill a Dragon, but what was that Dragon doing to warrant the intervention of the White God? Extruding itself too much into the mortal realm? Was Cowl active even then more than a dozen years before Storm Front? Dragons are immortal so Michael couldn’t have killed it properly except on Halloween, all he could have done is disperse it, and it would have eventually have coalesced back into a physical form. Perhaps initially an egg? Could that be what Cowl gifted to Ferro, the coalescing egg of Sirriothrax? Could Tunguska have been a previous dispersal of Sirriothrax reconciling the two apparent deaths? Morgan nuked a Naagloshii and it came back. Could the Tunguska incident actually be Grey Council not White Council?
Now that egg may be in Ferro’s vault, sitting on a ley line and growing, getting ready to hatch.