PondZombie, the stumps have to be totally waterlogged...may be easier to just cut off a foot or two of the tops than the frustration of burning up a 20# propane cylinder to just scorch a stump. Any way an excavator can get in and maneuver? A good sized track hoe could make quick work of the stumps, and make some really nice piles you could actually navigate around at a pretty reasonable price.....