[ChuckMcM]

Many desalination plants mix it back into the ocean, you pump more water than you are desalinating and the 'waste water' is a mixed brine at an acceptable salinity level.

That said with global warming melting a bunch of fresh water glaciers into the ocean, one of the side effects is lowering the salinity level. This suggests to me that boosting it slightly by desal efforts will be negligible at worst, and remediation at best.

And of course the quantities we're talking about are pretty much mouse nuts with respect to the entire ocean. But an interesting question to play with is when does a 'keystone pipeline for water' make sense? Clearly Boston would have not minded shipping snow to California to get rid of it this winter. China is working to reroute major water ways, could we manage flood levels on the Mississippi that way? I don't know but it is fun to imagine.

[chr1]

> That said with global warming melting a bunch of fresh water glaciers into the ocean

That's a very good point! Potentially desalination could help fixing problems of rising see levels too. There are many deserts that could become huge lakes (in Sahara, Persia, China) and eventually it should be possible to move enough water from sea to compensate for some of polar ice melt.