The reserve with an area of 63.79 ha (22.27 ha of buffer zone) [2] includes shallow and eutrophic Koskowickie Lake and its banks. The lake is part of the Legnickie Lake District, the complex of the oldest glacial lakes in Poland and the only lake district in Silesia. The majority of the reserve is occupied by the open surface of the reservoir - the lake littoral is generally limited only to the rush community constituting, however, more than 10% of the protected area. The Koskowickie Lake Trzcinowisko belongs to the largest in Lower Silesia. The plant communities of the reserve do not create protected natural habitats