The restoration of the anthropogenic Pławniowice water reservoir with the hypolimnion withdrawal method (the Olszewski's tube) began in December 2003. The decision to restore the reservoir had been taken due to its terrible condition resulting from the hypertrophy, which had been indicated by the research from the years 1993–1998.

The following paper presents the results of eight-year-long research into the formation of oxygen conditions and restoration settings. They were compared with the data obtained from the research before the restoration. Positive changes were witnessed. It was showed that grasping the changes in oxygen conditions enables the comparison of oxygen profiles in the same months in subsequent years. The ratio of anoxic water layer thickness to the oxygenated layer thickness was suggested as a factor characterizing oxygen conditions. The area described with an izooxa in the xy coordinate system was suggested as a factor [O2 mg/m2] allowing researchers to understand and describe occurring changes. It was observed that the oxygen solved in water as a result of the restoration occurred in the whole water column in the third decade of July. The oxygen concentration in the hypolimnion gradually rose in May, June and July each year. It was showed that the improvement in oxygen conditions stemmed from progressing oligotrophy of the reservoir.

The results of the first limnological studies of the Kuźnica Warężyńska anthropogenic reservoir, by flooding the sand mine excavation, in 2005, are presented. Measurements of water temperature and the concentration of oxygen dissolved in water were made every month, from April to December, every 1 meter deep from the surface to the bottom (22m). Kuźnica Warężyńska anthropogenic lake was classified according to Olszewski and Patalas as dimictic, eumictic, stratified, stable, and extremely limnic. In terms of the share of the littoral zone in the total area, the reservoir is classified as grade II according to Dołgoff, where the pelagic zone is similar to the littoral zone. After 14 years of the reservoir's existence, during the summer stagnation period, the oxygen in the hypolimnion is completely depleted, from the 10th meter deep to the bottom, 22m. The analysis of the vertical distribution of the regression coefficient for the relationship between water temperature and the concentration of dissolved oxygen in water indicates the influence of the oxygen-free groundwater supplying the reservoir as a factor that may, in addition to the decomposition of organic matter, initiate anaerobic processes in the bottom water layer of the reservoir. When circulation ceases, the bottom eruption of oxygen-depleted groundwater is, during the summer and winter stagnation, a factor that shapes the anaerobic environment in the bottom layers of water early, initiating the internal enrichment process. Hydrological conditions, morphometry and thermal-oxygen relations of the Kuźnica Warężyńska reservoir are favorable for undertaking technical measures - changing the method of draining water from the surface to the bottom - to protect the quality of water resources.