**11. Conclusions**

Conducting the studies on the conditioning and effects of physico-chemical properties of the water in the Turawa reservoir in the hydrological years 2004–2006 confirmed the hypothesis that its ecological status was deteriorating due to strong agricultural and industrial anthropopressure.

The changes of physico-chemical properties of the reservoir were determined by the quality of inflowing river water, mainly the Mała Panew river, and inflow of pollutants from localities and resorts without the appropriate sewage systems. Moreover, the biological and chemical processes proceeding in the reservoir resulted in the changes of physico-chemical properties of water.

According to the guidelines of monitoring programme of lakes, the Turawa reservoir is characterized by moderate susceptibility for anthropopressure according to morphometric, hydrological and basin characteristics. However, the water of the reservoir could have been classified as the third class of purity, that is, as water strongly polluted.

According to the qualitative classification of surface water, the reservoir was classified as unsatisfying (class IV) or bad (class V) with respect to oxygen-related parameters (BOD5 and CODMn,), total organic carbon, microbiological parameters and also to the concentration of heavy metals such as lead and cadmium.

In 2004–2006, due to strong eutrophication the following physico-chemical parameters of water worsened: colour, odour, oxygen saturation, transparency, pH, BOD5 and CODMn. Positive tendency of decreasing water hardness and concentrations of calcium, magnesium and sulphates took place.

One of the largest threats of ecological status of the reservoir was water eutrophication which threatens ecosystem operation. The most important threats were oxygen deficit in deep areas of the reservoir which is dangerous for aerobic organisms, oxygen oversaturation of epilimnion, decrease in water transparency, pH increase, accumulation of organic matter, reservoir overgrowing, deterioration of taste and smell, and release of phosphorous compounds in anaerobic conditions. Progressing degradation of aquatic environment decreases the usable value of water, lowers the aesthetics of the environment and management of all the water bodies.

Deteriorating ecological status of the Turawa reservoir was required to take immediate comprehensive measures to prevent it from total degradation. Remedial propositions were as follows:


After 10 years, the physico-chemical parameters are being measured again to assess the results of remedial actions.
