Abstract
The aim of the study was to determine the impact fish farms have on water quality in rivers. An experimental system for estimating the amount of pollution produced by aquaculture and discharged into surface waters was tested through environmental research. The impact of clarifying ponds on the quality of post-production water was determined. Measurements of the physicochemical parameters of water discharged from fish farms were used to determine the impact selected pollutant loads had on receiving river and/or basin waters. The study, which was conducted between April 1999 and June 2009, focused on examining interactions between surface waters and six rainbow trout, Oncorhyncus mykiss (Walbaum), farms, two carp farms, and one hatchery. The fish farms were located on the Drwęca, Marózka, Naryjska Struga, and Wąska rivers, and on one unnamed brook in the Pasłęka catchment area in northern Poland. All of the fish farms studied had a negative impact on water quality. Analyses of indicators of the chemical substances discharged from trout farms indicated there was relatively quick improvement in river water parameters.