Trophic Water Assessment of the Small Retention Reservoirs Blizne and Cierpisz in the Podkarpacie Region (Subcarpathian Province)

The paper presents an analysis of the trophic status of two small retention reservoirs located in the Subcarpathian region: Blizne reservoir on the River Ladzierz and Cierpisz reservoir on the River Tuszymka. The capacity of the reservoirs is respectively 137,000 m³ and 22,000 m³ and they occupy an area of 11.46 and 2.3 hectares. The study was conducted from May to October in 2013 and in 2014. Samples of surface water were collected from two locations for each reservoir. Assessment of the trophic status of the reservoirs was based on the concentrations of phosphorus, nitrogen and chlorophyll a. Criteria available in the literature were used to assess the trophic status. The progress of eutrophication was also evaluated on the basis of the Trophic State Index (TSI). Analysis of the results showed that in the studied period the water of Blizne was on the border of eutrophic and hypertrophic. The fertility of the water of Cierpisz in the analysed period deteriorated from the eutrophic state to the border with hypertrophic.