Fisheries adapted. Pollution has seen a massive decline. The zebra mussel...well that's nature, and as much as can be done about it has been done, but you can't really stop nature. As to water levels --
http://www.waterlevels.gc.ca/C&A/NetworkMeans2013.pdf
-- it's at a low ebb right now, but isn't at record lows at all. If you have memories of much higher levels, those were likely historic highs.
Plenty is being done for the Great Lakes. More can be done, but pointing back at the 70s doesn't demonstrate that things aren't being done today.
How exactly, and what from, do they need to be protected?
Also: why the ad hominem? There was nothing idiotic about my simple question.
Stop downvoting and answer the question.
>over-fished, ... polluted the living hell out of them
Zebra mussels you might be able to claim damage the lake, but the complaints against them are certainly primarily based on nuisance, so I'll exclude them.
Since zebra mussels became established in Lake Erie,
water clarity has increased from 6 inches to 30 feet
in some areas. … One drastic impact of the zebra mussel
invasion is the near extinction of native American
unionid clams in Lake St. Clair and in the western
basin of Lake Erie.
The way you asked it was like "What problems?" when it's obvious that a water-system that vast needs controls or it'll be abused and ruined for everyone.
They've been over-fished, the industries of the surrounding area polluted the living hell out of them up until the 1970's, they've been invade by Zebra mussels and the water levels are at record lows. Places I swam as a kid don't even exist any more - the water has moved out a hundred yards from the old shore.