What does this mean? North is upper on a map? Does it deal with dams? What if there is no dam?

Thanks

Upper refers to end of lake that water flows into.  Lower refers to area of lake that water flows out.

"Upper refers to end of lake that water flows into.  Lower refers to area of lake that water flows out."

x2.....   Most of the time the upper end is more northern than the lower end just because in most parts of North America water flows from North to South.  However there are many places this isn't true.  A general rule of thumb for many reservoirs is that the upper end will have shallower, dirtier water while the lower end will have clearer, deeper water.