The Collaborative International Dictionary of English v.0.48:

Plashy \Plash"y\, a. [From 1st Plash.]
   1. Watery; abounding with puddles; splashy. "Plashy fens."
      --Milton. "The plashy earth." --Wordsworth.
      [1913 Webster]

   2. Specked, as if plashed with color. --Keats.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "plashy":
   aquatic, aqueous, dirty, hydrated, hydraulic, hydrous, liquid,
   miry, mucky, muddy, oozy, slabby, slobby, sloppy, sloshy, sloughy,
   sludgy, slushy, soft, splashy, sposhy, squashy, squelchy, squishy,
   swashy, turbid, waterish, watery