Representing a key water source for tin and iron mining as well as ore dressing, the still functional installation of the Horní Blatná water ditch dates back to 1540-1544. Being 13 km in length it stands for the longest water ditch in the Czech part of the Ore Mountains. Further it illustrates high standards of technical work for the purpose of water management during the 16th century. There are numerous additional installations to control water flow, these are: an inlet structure, 10 overflow spillways at the intersections with small creeks, 25 bridges and culverts, 39 sand and gravel traps, and, three bridges to facilitate walking along the canal. The ditch starts 1.5 km west of Boží Dar, where the water of the Černá creek is directed into an artificial leat. Then it crosses the municipalities of Myslivny and Ryžovna to Bludná, the first large centre of mining and dressing. After by-passing the Blatenský hill, it approaches the major tin mines of Laurentius, Konrad and others around Horní Blatná. In places, the water ditch is up to 2 m wide and 1 m deep. It´s waterbed is mounted by wooden embankments on both sides.