Hudson Bay Fresh Water Project

Doing this will not only create one of the worlds largest fresh water supplies, but also help counter the melting fresh water ice in the ocean.  we can deal with water level rise, we cannot deal with the ocean currents slowing down.  That could be catastrophic.

The islands on the north side could be closed with an automated earth moving process.  take the soil from areas that will eventually be covered with water from sea level rise.  terraform it to accommodate more species when the water does rise.

This should be done sooner than later given the long game approach.  If you dam it now, the water will rise and the lake will not.  we will have less water to desalinate.  over time, rain should lower the salt content as it fills with fresh water.  if we do most of the desalination heavy lifting sooner, it would also be easier because right now it is more concentrated, and requires less processing.  Desalination tactics are far and wide, but i think the best one is using mother nature.  

1) allowing sea water into inlets, and having the sun evaporate it over time, could allow us to dry out entire lakes.  if we place them on the upwind side of the lake, the evaporated water would come back down as rain into the bay, and boom, natural desalination process.  we just need to  clear the salt, and open the dam every time it dries out. 

  a) If we position the lakes near the ocean as well, we could push the salt out the  side of the lake into the ocean.  that is the key part of the process, as the ocean needs more salt to keep current.  a freshwater lake does nothing.  

2)  Let it flow.  If we create a river flowing out of the new lake, and keep adding water to it, over time, the lake will naturally become fresh water.  The trends will be brackish water near rivers at first and for many years unless given a boost.