This pond was mostly blue when I was here in 2004 ( http://www.pbase.com/listorama/image/52410105 ).
The white substance is either the salt or potash that used to be in solution. At the far
end of this "pond" a road grader or similar machine was harvesting the stuff.


This shot was taken at the center of this WikiMapia aerial view (click on any
rectangle): http://www.wikimapia.org/#y=38496879&x=-109681621&z=16&l=0&m=a&v=2.

.