Re: Is barium found in lake water? If so, how can I test for it?

It depends on the lake.  Some lakes may contain some dissolved barium.

The best way to test for barium, if you don't have an atomic absorption
spectrometer, is to concentrate some lake water (boil it down), and add
a bit of sulfuric acid.  Barium sulfate is a white precipitate (a solid
that will form in the solution if there is barium there).

This is known as a "qualitative test" for barium.