How does one translate snow water content report into inches on the ground?

There's no direct conversion, but some rule of thumb estimates like 1 inch of water content is about 1 foot of snow, but these are very approximate. The density of the snow varies a lot depending on moisture content of snow storms, and how consolidated it gets from freeze/thaw cycles and rain on the snow. If you can find stations in the area of interest that report both snow depth and water content, you can approximate a conversion number for stations in the area that only report water content. But local conditions at the station are really important (elevation, slope direction, exposure to sun, etc)

Sorry, wish there was a simple conversion to get accurate results, but its not that straightforward.