Assertion: aquifer's porosity | /r/HasProperty | low
Facets:
Source sentences:
text: The lower transmissivity values (less than 50,000 feet squared per day) shown in figure 56 mark places either where the upper confining unit is thick (southern Florida) or where the aquifer system is thin or its porosity and permeability are low, or both (areas near the updip limit of the aquifer system).