| Summary: | The paper presents the results of the research conducted between November 2008 and October 2009. The research included seasonal dynamics of the flow and runoff of phosphorus compounds (TP and P-PO43-), as well as Ca2+ and Mg2+ from 13 partial drainage basins of the River Drwęca. Water levels were registered automatically every day by recorders, and measurements of the flow were conducted once a month. Major differences were found in the water abundance as indicated by specific discharges in individual, partial drainage basins: from 1.87 dm3 s-1 km-2 (Lubianka - a lower part of the River Drwęca drainage basin) to 8.22 dm3 s-1 km-2 (Gizela - an upper part of the River Drwęca drainage basin). The studied rivers were characterised by very diverse average content of total phosphorus compounds: from 0.047 mg dm-3 (Iłga) to 0.816 mg dm-3 (Sandela); calcium: from 47.18 mg dm-3 (Iłga) to 131.65 mg dm-3 (Trynka); and magnesium: from 9.71 mg dm-3 (Wel) to 36.76 mg dm-3 (Struga Rychnowska). Analysis of variance carried out on hydrochemical properties of the studied rivers divides the rivers into two separate groups: rivers with much higher content of phosphorus, calcium and magnesium compounds (Struga Rychnowska, Trynka, Ruziec, Lubianka, Kujawka, Sandela and Gizela), and a group of rivers with low content of these compounds (Brynica, Brodniczanka, Skarlanka, Wel, Iłga).
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