Luxembourg borders Belgium, and Lac de la Haute Sûre at its closest point is only two miles from the Belgian border; so, it is conceivable that Belgians might get water from that lake.

>(CS) Authorities have decided to stop using water from the Lac de la Haute Sûre for drinking water treatment, following the spread of a pesticide in the water after a spill in Belgium.

I know it very well, as I live in Luxembourg[1] and I have to explain it to everyone I spoke to in my native country, Italy (normal questions are "so, how is it your life in Bruxelles?" "what about your living in Belgium" etc..)

So thanks for your unneeded geography lesson and now if you would be so kind to open the link you'll read why Luxembourgish newspaper were talking about some pesticide in a Belgian lake...

[1] and if we want to be really really precise, the south province of Belgium at the border with Luxembourg and France is called Province of Luxembourg, so we should talk about Province of Luxembourg and Grand Duchy of Luxembourg.