To be fair if you are evaporating water you could be losing some of it outside of the Great Lakes water basin, you are increasing the evaporation rate above what is natural for that area of land.

However the place for that to be least likely to be a problem would be Wisconsin with their evaporated water blowing east over top of the Great Lakes 90% of the time and any excess humidity will rain back down or slow down lake evaporation because the air over the lakes is already saturated with humidity most of the time.

But there still can be a problem if all that water is being pumped from deeper underground aquifers instead of surface water, so the source still matters. Those aquifers still should replenish fairly quickly in that area, but draining aquifers can happen in decades if the demand is there, while replenishment from non-surface aquifers can take hundreds of years even in water filled areas. And in certain ground compositions, underground aquifers can collapse and subside if the water is mostly drained, never again being able to hold that much water again and causing changes in surface topology.

Hope they don't find out how much is lost naturally to evaporation each year..