The term regale, here, refers to the granting of royal privileges or rights[1] (droit de régale) in this case to permit the use of water for mining operations in the Harz mountains of Germany.

[3][4] The water system covers an area of roughly 200 square kilometres (77 sq mi) within the Lower Saxon part of the Harz, the majority of structures being found in the vicinity of Clausthal-Zellerfeld, Hahnenklee, Sankt Andreasberg, Buntenbock, Wildemann, Lautenthal, Schulenberg, Altenau and Torfhaus.

[2] In German, the term Oberharzer Wasserwirtschaft ("Upper Harz Water Management") has also been frequently used to refer to these historic facilities.

But this is not precise enough, because in the last hundred years an intensive, modern water management system has been put in place in the Upper Harz in the form of a number of new dams and their associated structures and ditches.

[7] The taxes raised from this contributed significantly to the revenue of the royal houses in Hanover and Brunswick-Wolfenbüttel and helped to secure their positions of power and influence within the Holy Roman Empire.

In the Upper Harz, vein mining (Gangerzbergbau) was the main form of extraction, with excavation following the near-vertical lodes straight down into the earth.

Initially it was mopped up using men standing on ladders, the so-called Wasserknechten ("water servants"), with their leather buckets.

[5] As a result, mines - particularly the richer, deeper ones - started to use hydropower systems, able to work continuously, 24 hours a day.

Although the Upper Harz, with an annual precipitation of over 1300 millimetres per year, received copious amounts of water, the mines often lay high up in the mountains close to the watersheds where there were only a few streams of any size.

[10] Deep shafts, however, demanded correspondingly high levels of energy to lift ore and pit water.

[12] Several smaller dammed ponds still belong to the Lower Saxon State Forestry Department or are even in private hands.

Important mines also had a reciprocal water wheel which was used to provide power for transporting the ore and the material to be crushed.

The ditches are supply channels almost parallel to the terrain contours, with a very slight incline of around 1-2 per mille and are accompanied by an inspection path.

Due to the sheer number of structures and the length of the ditches the Upper Harz Water Regale is best explored on foot.

Visitors can get to know about the typical elements that make up the Upper Harz Water Regale by means of information boards along the clearly marked routes.

The Black Death in the Middle Ages depopulated the Harz to a great extent and almost brought mining operations to a standstill.

[6] But it was his son, Julius, Duke of Brunswick-Lüneburg, who gave added impetus to existing mining operations in the Upper Harz and initiated the creation of a large number of ponds and ditches.

The lack of water following months of little rain or long periods of frost was time and again a limiting factor for the mines.

It collected water from the mines in Bockswiese, Lautenthal, Zellerfeld, Clausthal and Wildemann and led it to Gittelde on the edge of the Harz.

[5] These structures contributed significantly to the Harz becoming the largest industrial region of Germany in the early modern period.

Of course, with the introduction of the steam engine, the difficulties of acquiring coal in sufficient quantities was also a factor until the construction of the Innerste Valley Railway.

No public money is spent; the cost of maintenance, a seven-figure sum annually, has to be borne by the Harzwasserwerke through its sale of drinking water.

[12] In addition to the facilities entrusted to the Harzwasserwerke there is a large number of dam ruins, tunnel entrances and several hundreds of kilometres of ditches that are not maintained.

That means that they are like the ruins of castles, subject to very gradual decay, but which may not be destroyed by modern measures without legal permission under conservation law.

Nevertheless, the Upper Harz Water Regale, is the largest and most interconnected system of its kind in Europe, with significantly more dams and ditches as well as larger structures than all its counterparts elsewhere.