This study on the effect of a small retention system on the temperature and chemistry of a mid-forest headwater stream has been conducted in the valley of the Kamienna Stream in northern Poland. The catchment of the stream is composed of glacial and fluvioglacial sandy deposits, which are deeply dissected by the stream valley. The catchment is covered mainly by forests with the predominance of beech, pine and spruce on the plateau and alder in the valley bottom. Small retention objects were built in 2007 and include a cascade of a few dammed shallow lakes of varied area. The stream’s water was sampled at 8 stations distributed along the stream. The sampling took place at monthly intervals in 2013-2014. The temperature, pH and conductivity were determined on situ. The content of major cations and anions was analysed using an ion chromatography technique. The results showed only a limited effect of the small retention system on the water parameters studied. The warming effect of the dammed lakes was visible, although it disappeared at a short distance from the stream’s flow out of the lake. The stream’s flow through the retention objects resulted in a considerable increase of the Na+ content and a slight decrease in the content of SO42- and dissolved O2. Conductivity and the content of Ca2+ and HCO3- showed an increasing tendency down the stream and no effect of the retention system was visible. Concentrations of the remaining water ionic components did not adhere to any distinct tendency. Water presented the calcium-bicarbonate character at every sampling point and over the whole study period.  

24.2.2019