Seasonal flooding and water retention within low lying areas or areas associated with water drainage pathways creates unique and productive habitat within the landscape. The area of wetlands that are regularly flooded and contain substantial amounts of emergent and submerged vegetation is called hemi-marsh. The area of hemi-marsh is estimated for selected wetlands in PEI National Park during late summer each decade using satellite and digital ortho-photo images as a measure of wetland productivity. The amount and rate of change of hemi-marsh area between decades is tracked and compared against historical levels to evaluate ecological integrity within the park for this ecosystem feature.