Summary:

The paper present the detailed assessment of water retention possibility in the lakes situated in the Struga Dormowska River. These activities were important to increase satisfy water needs warranty of fish ponds.
Struga Dormowska is the third rank river, the left tributary of the Warta River. The area of the catchment amounts 57.2 km2. The catchment has an agricul-ture-forest character and high lake density. Struga Dormowska flow through twelve lakes, which have an area of 240 ha. The area of each lake range from 2 to 79.6 ha. The catchment has a very small water resources. Specific runoff of the catchment equals about 2 dm3.s-1.km-2, and runoff coefficient about 0.1.
The researches reveal that increase of lakes water retention allows to obtain high amount of disposal water, that allows to increase water needs of the fish ponds warranty satisfy located in the middle and lower part of the river. The estimation was based on amplitudes of water level in the lakes, elevation-storage curves and inventory of hydraulic structures along the river.
Damming of the water in the seven lakes from 0.2 to 0.3 m in natural water level oscillations allows to gain about 0.4 mln m3 water in the usable retention layer. That allow on smoothing discharges in the river in the range from 6 to 21% in the wet and dry years respectively. The damming of the lakes should be done from March to July. In the other period it is necessary to restore the natural river continuity. Damming the water in the lakes have a positive impact on water condi-tion in the adjacent areas.