mineral buildup on memorials

[Norman Watts <Norman_Watts@zzzzzzz>]

I recently spent a day wandering around the National Mall here in DC
looking at the various memorials. The brand new World War II memorial
and particularly the relatively new Roosevelt memorial are built from
amazing amounts of granite. The former in grey and the latter in a
dark red color. At this time of year the fountains and waterfalls
have been laid dry and you can see the heavy mineral deposits on the
stones. The Roosevelt one in particular, having a dark stone and many
splashing falls, has large white and yellow-green stains on it that
the all the rain this winer still hasn't touched. The memorials look
quite ugly and neglected. Is there something the Park Service (I
assume they are responsible) could do to prevent this? Maybe use
somewhat softened water rather than just straight city water? Or is
there a mild (environmentally not to grim) way of cleaning them each
fall? What would be better in the long run? Just curious.

n