These numbers aren't off the top of my head, I helped my parents put in a rock sea wall on Muskegon lake 8 years ago to help prevent the erosion of their property due to the wave action. That sea wall is now a pile of rocks with 50+ yards of dry land BEYOND it.
My grandfathers home was built on a dredged channel allowing significant sized watercraft for the homeowners. (Channel View Drive, Spring Lake) A kids rubber raft barely fits through that channel now.
My stomping grounds as a kid (I should say paddling grounds) was a called Norris Creek in Fruitport Michigan, it was a wonderful fishing place that is now a mere ditch with a trickle of water flowing through where there use to be productive swampland.
Don't challenge me on this. I grew up there and have seen the decimation caused by the drop in the water table. You are flat out wrong and misinformred to conclude otherwise. I know that from personal observation. Fishing is all I did from 6 years old to 17, then girls took over my interest, but the fact remains that you can barely get a canoe through that once prolific fishing ground.
Water is the next oil, probably 100-200 years out, but it's a fact.