Efficiency:
If the water isn't flowing, simply store the ore in the river until it moves again and then collect them all
Reaction speed for the overall script, I noticed it's a tad slow on a constant speed. Maybe add the option to randomize the reaction speed of walking, mining, ect. (Bot mode or Human mode?)
GUI:
Option to buy Prospector gear with the stored nuggets and wear it(Progressive prospector gear mode?)
Option to not fix the flow of the water if the wheel is broken
Reaction speed modes as I have mentioned in the efficiency (Human, Bot, fast, medium, slow, passive, ect...)
Here's a small feedback for you Czar