Grough

[…] leaving you "pathless" in the middle of the moor. […] you step into the nearest grough […] after a hundred yards or so, the grough that you have so wisely chosen, now has sides of eleven feet high and according to your compass, has wandered off course and is now definitely not taking you in your intended direction.

The shallow slow-running groughs fed the hag with a trickle of coppery water.