Who first used water ballast and when?

When was water first sanctioned in contests? I read
somewhere in Soaring that some of the pilots at Marfa
back in the 60s were putting 'suspicious looking packages'
behind them on the spars. The inference was that they
might have been heavy metal and possibly illegal.
Weren't gliders once weighed at contests?

At 18:48 13 October 2006, Nick Olson wrote:
Martin Simon's book on Schweizer gliders referring
to the 1-21 states that the Germans had proposed the
idea as far back as 1934 and I think Riedel in one
of his book talks about a Minimoa with provision for
water ballast -although don't think it was dumpable.