The Demer river 's drainage basin covers most of the central and southern part of the province , except for the southeastern corner , where the Jeker ( in French : ( le ) Geer ) runs past Tongeren and into the river Maas ( in French : ( la ) Meuse ) at Maastricht .
The Demer river 's drainage basin covers most of the central and southern part of the province , except for the southeastern corner , where the Jeker ( in French : ( le ) Geer ) runs past Tongeren and into the Maas river ( in French : ( la ) Meuse ) at Maastricht .