I want to find an art supply store in Paris, on the Left Bank, 5th or
6th Arrondissement where Arches watercolor paper ( manufacturer's full
name is Moulin à Papier d'Arches)is sold. Telephone number and Email
address would be helpful.

Hello,

There's a chain of art supply stores in France called Graphigro
(www.graphigro.com) They are market leader in france and offer over
18000 products, they are a kind of supermarkets for arts supplies.
They offer a very big variety of papers.

There's a graphigro store in the 6e arrondissement:
133, Rue De Rennes
Phone: 0153/636000
fax: 0145/447000
They don't have an e-mail adress on their site, but you can fill in a
contact form on their website.

additional links:
www.graphigro.com
www.miniaturama.com

search strategy:
on French Google (www.google.fr), only French webpages:
"magasin arts paris"
"papier arche paris"
"magasin paris materiel art"

Should you have any more questions or comments, feel free to ask, I'll
see what I can do.