Otherwise it would fill the mine, which is up to 230 metres deep.This is achieved by means of shafts (Schlitzschächten) through which the water flows back into the groundwater.

The source of the Schwalm is in a wetland area south of the German village of Wegberg-Tüschenbroich at an elevation of about 85 m above NN.

Of its total length from this source to its mouth on the Meuse, near the village of Swalmen at about 12 m above NN, 13 kilometres of the river run through Dutch territory.

Parts of the river which, for example, run past the villages of Wegberg, Niederkrüchten, Schwalmtal, Brüggen-Born, Brüggen and Swalmen, form natural meanders.

Frogs, dragonflies, damselflies, bluethroat, kingfisher and golden oriole are to be found as are water crowfoot, bog myrtle and other rare plants.