Quality of effluent water from earthern fish ponds in Hungary

Abstract

The water quality of running water is determined mainly by the type of human activities within the catchment area, including fish culture. The introduction of polyculture, the intensive application of fertilizers, the use of manure and the development of fish-cum-duck culture have influenced water quality in fish ponds and in pond effluents in both the growing and harvesting seasons. Natural waters which serve as water supply for fish production systems are characterized by an increased nutrient load. Government order No. 3/1984.(II.7.) OVH, based on the Government order No. 32/1964. (XII.13.) deals with the Water Utilization Act which is concerned with the state requirements on release of industrial effluents. This Act divides the area of the country into «zones of water quality protection», and determines the limits of pollution load for each water quality zone including penalties in case the limits prescribed in the Act are exceeded. Fish farms are also included into this Act. In 1988, a 2-year research programme was started to analyse the effluents of extensive and intensive fish production systems from both environmental protection and economic standpoints. The goals of this research programme were: (1) to determine whether fish farm effluents meet the state requirements given under Government order No. 3/1984.(II.7.) OVH at all times of the growing season and what pollution is caused in the recipient; (2) to describe the changes of water quality in the inflow and the outflow waters and in the recipient during the growing season and to collect data on possible water quality changes due to the seasonal drainage. These data should serve as a base for describing nutrient pathways in order to develop strategies for impact mitigation