Aim of the study:
Study of the effects of the microbiological bioremediation process carried out as part of the purification of the reservoir in Kamienna Góra.

Material and methods:
A number of field measurements were made, i.e. thickness of bottom sediments, light transmission, and physicochemical analyzes of waters. Activities undertaken in the bioremediation process were described. The final effects have been characterized.

Results and conclusions:
The microbiological bioremediation process has contributed to the reduction of bottom sediments (organic fractions) by 30 - 100% at selected measuring points. There was an improvement in the euphotic zone conditions from 70-100% in the examined points. The level of organic pollutants in water has also partially improved. The concentrations of the studied biogens did not decrease, and even in some points they increased in 2018. Despite visible changes in the water quality in the reservoir, and almost complete elimination of organic fractions in bottom sediments, an increase in nutrients in the flood waters could be expected. In the last year of research, complete elimination of algal blooms was noted and ecotones were located in places of their earlier occurrence. The reservoir is still exposed to pressure from pollutants brought in by Zadrna's waters. If sources of pollution are not eliminated, this type of treatment will have to be repeated in subsequent seasons to maintain the quality of the reservoir water.