Owens Lake [2] to the south of Mono Lake is gone. It was larger than Mono Lake. Lake bed salts blown by the wind are pretty toxic, and Los Angeles was required to use some water to reduce dust.

The largest freshwater lake west of the Mississippi used to be Tulare Lake [3] in central California. It's gone and the southern San Joaquin Valley no longer drains to the ocean. Salts and other junk is slowly building up.

[1] https://en.wikipedia.org/wiki/National_Audubon_Society_v._Su...

[2] https://en.wikipedia.org/wiki/Owens_Lake

[3] https://en.wikipedia.org/wiki/Tulare_Lake