Abstract
Water quality and fluctiation pattern in water level of 38 small irrigation ponds were investigated in Hokudan- cho, Hyogo Prefecture, West Japan. Temperature, water temperature, pH, electric conductivity (EC), dissolved oxygen (DO), N02-, N03- NH4+, SiO2, PO43-, chemical oxygen demand (COD) and water level were surveyed in each pond from May 2002 to April 2003. The result showed that there was not so much difference in water condition of among ponds, because water is frequently pumped from a pond to another pond. The existence of water plants and polluted water from residences influenced water condition. The water level of most irrigation ponds fluctuated dramatically from spring to the end of summer.
