Is there any experience in using depth measurement data (average depths calculated in "volumes and areas") for comparisons? Is it possible to compare such data from different months for the same area? (We want to document mud degradation in relatively shallow fresh water lakes.) Where are the limitations for such comparisons?

Have you considered exporting your data from Reefmaster to say a Shapefile for import into something like QGIS so you can do your volume and area analysis work?