Roter Graben is an artificial trench built in the 17th century. Running along the foot of the Davidschacht Tailing, Roter Graben drains the Freiberg mining area. It runs between Halsbach and Halsbrücke, largely parallel to the Freiberger Mulde River.
As a branch from the trench of the middle Ratsmühle northern from Halsbach, the water from the Freiberger Mulde River supplies the Roter Graben. Running on the west side of the Freiberger Mulde River, it passes the mouth of the Königlich Verträglicher Gesellschaftsstolln to the north. From this tunnel, it takes in draining pit water. Roter Graben continues to pass through the mouth of the Thurmhof Hilfsstolln and the main break in the old Tiefen Fürstenstolln and in turn absorbs its pit water.
It runs to the Freiberger Mulde River through several surcharges. The name refers to red, iron-rich precipitates in the trench. Roter Graben is currently heavily silted.
Roter Graben contains approx. 13,000 m3 of ferrous mud. Since the trench is leaky, there is a risk of heavy metal pollution for the groundwater. The trench also endangers surface water if it should overflow. If Freiberger Mulde River floods, there is a risk that trench sediments will be mobilized and retaining walls will be torn away. Thus, Roter Graben endangers the soils on the banks of the Freiberger Mulde River during floods.