Protection of surface water against contamination by wetland systems in Poland

Facilities constructed in order to protect streamS against storm water in the Gdan«sk region are described. The first of them is located on the Rynarzewski Stream (water flow 25 l/s). The stream is the main tributary of the Jelitkowski Stream which in turn drains to the Baltic Sea in the area of popular beaches and hotels. Results of analyses indicate the improvement of water quality in the stream and along beaches in this region. Another facility is situated on the Swelina Stream (water flow 30 l/s). The stream is fed with storm water originating from residential districts. In order to improve water quality a pond was constructed supported by a subsurface flow filter (HF-CW type). After implementation of the system substantial improvement of water quality occurred. In order to protect drinking water intake for the city of Gdan«sk against surface and point sources of contaminants a hydrophite treatment system was constructed in Bielkowo. The system consists of two subunits: wet unit (pond), filled with water all the time and dry unit (extention of the pond), designed for storm water. In the wet unit dams constructed of medium size sand are placed. The system, especially the dams, is inhibited with reed. The drainage systems collect water percolating through the dams, and directs it downstream. The system was constructed in 1997. Since then it has proven a substantial improvement of water quality discharged of inflowing loads, on average.