The Hebrew agam refers to a standing pool, marsh, or reed pond. It appears in descriptions of Egypt's waterways in the exodus plagues and in prophetic imagery of desolation.
The agam appears prominently in the first plague of Egypt (Exodus 7:19), when God commanded Moses to stretch out his staff over the rivers, canals, and ponds of Egypt, turning all water to blood. Every body of water — from the mighty Nile to the smallest pool — came under God's judgment. The same word appears in prophetic reversal: Isaiah 35:7 promises that burning sand will become pools of water in the age of restoration. Judgment becomes blessing; the barren land flows with water.