Bromate forming in open water
The water referred to in the article was being stored in a reservoir after being treated with chlorine.  It is the combination of chlorine and sunlight that facilitates oxidation from bromide to bromate.  

So, no, this is not applicable to natural bodies of water, only bromide containing water which has been artificially treated with chlorine.

See Bromate ion formation in dark chlorination and ultraviolet/chlorination processes for bromide-containing water for more information.