Through the door with the password written above it, I found a room filled with the equipment which was polluting the river. Was given choice to leave the equipment alone or destroy it. Chose to use destroy multiple times and eventually the equipment broke, taking 15 points damage on every player, and killing my magic user in training.
Moved on and found a room with lizard man slaves. They passed on:
Journal Entry 35 - details of Yarash's experiments on lizard men, and a password
The password translates as SAVIOR, used when meeting lizard men apparently.