You must have been reading my mind and holding that packet of Belle Saison yeast we received at the Philly conference.
In my opinion, there isn't a definitive profile for what a saison is brewed with. However, you can get an idea of what might work well by studying the locations of the various Belgian profiles included in Bru'n Water. Given the location of Brasserie Dupont in Hainaut, I'm inclined to lean toward that profile as an indicator. In the case of brewing a pale beer like a saison, the water would have to be pre-boiled in order to reduce the alkalinity to a reasonable value. Bru'n Water assumes a very modest ending bicarbonate content of 80 ppm. However I think that with proper procedure, a brewer could have actually got the bicarbonate down to 60 ppm without much problem. Therefore, I recalculated the calcium content for the reduced bicarb. The revised Henegouwen/Hainaut (boiled) profile is shown below.
Ca 30 ppm
Of particular note is that there is a modest amount of sulfate in the water. This conforms to my findings that sulfate does help dry the finish of a beer and a saison must have a dry finish. Don't listen to Dr. Chloride and eschew sulfate whenever noble hops are used in brewing. Modest sulfate content is your road to saison success.