SLUDGE is a playable word

sludge Scrabble® Dictionary

verb
sludged, sludging, sludges
to form sludge (a muddy mass or sediment)
60 Playable Words can be made from "SLUDGE"
   2-Letter Words (5 found)
   3-Letter Words (17 found)
   5-Letter Words (13 found)
   6-Letter Words (1 found)