This is the Souillacroute to Rochester Falls. I don't give any guarantee that it is a safe route. You will use it in your own responsibility.
When you see the area with the little houses on the right the road will become a dirt road. If you are lucky you can park the car there, and walk (if it is not too hot).
If you go further to park near the falls, be aware of people asking you to look after your car. If you don't pay them they may pay you back with scratches or a flat tyre.