1) Alluvial deposits 2) Alluvial plains 3) Brackish water locales 4) Certain stars 5) Fertile-soil areas 6) Flood-prone areas 7) Fluvial plains 8) Fraternity letters 9) Greek letters 10) Mississippi sights 11) Mouth features 12) Mouth formations 13) Mouth parts 14) Nile and Mississippi 15) Pointed river formations Found on https://www.crosswordclues.com/clue/deltas