Wągrowiec is a city known to hydrologists everywhere on account of an unusual phenomenon witnessed here. The two small rivers that flow through the city, viz. the Wełna and the Nielba, manage to intersect without their waters commingling. Pride in this left-field phenomenon is only marred by the fact that the bifurcation in question was brought about by human agency. The Cistercians managed this in 1830 while carrying out irrigation work on their property. Still, this does not make the phenomenon any less rare in Europe.