The rice terraces of Bali are extraordinary for their irrigation sytem called Subak. The system was developed in the 9th century and consists of the forests that protect the water supply, terraced paddy landscape, rice fields connected by a system of canals, tunnels and weirs, villages, and temples of varying size and importance. The water managements is under the authority of the priests in water temples, who practice Tri Hita Karana Philosophy, a self-described relationship between humans, the earth and the gods.