Editing Oker (section)

== Course ==
[[File:Oker.JPG|thumb|left|Confluence of the Oker (left) and Gerlachsbach (right) in [[Altenau (Oker)|Altenau]]]]
[[Image:Oker im Okertal.jpg|thumb|The Oker Valley (''Okertal'')]]
[[File:Okertalsperre staumauer seeseite.jpg|thumb|left|Oker Dam]]
[[File:OkerVerlobungsinsel.JPG|thumb|The ''Verlobungsinsel'' and Verlobung Bridge in the Oker valley near [[Romkerhall]]]]

The Oker rises at about 910 metres in the [[Harz National Park]] in a boggy area on the [[Bruchberg]] in the [[Harz]] mountains of [[Central Germany (geography)|central Germany]]. This early section is known as the ''Große Oker'' ("Great Oker") and it is impounded below [[Altenau (Oker)|Altenau]] by the [[Oker Dam]]. From the dam wall to the former village of [[Oker (Goslar)|Oker]], which is today part of [[Goslar]], the Oker is on certain occasions suitable for [[canoeing]]. This section, often called the "Oker Valley" (''Okertal''), includes the [[Romkerhall]] Waterfall. Here the ''Romke'' stream drops about {{convert|64|m}} in height over a [[waterfall]] laid out in 1863 into the Oker. Downstream in the river's fast-flowing waters, the ''Verlobungsinsel'' ("Betrothal Island") is to be found. Left and right of the Oker in this area are many [[crag (climbing)|crag]]s that are popular with [[climbing|climbers]].

In the Goslar vicinity of Oker the river is seriously polluted with [[heavy metal (chemistry)|heavy metal]]s from the [[slag heap]]s as well as [[groundwater]] and [[surface runoff]] from the metal [[smelter]]s there.

[[File:OkerWehrOker.JPG|thumb|upright|left|The Oker Weir in [[Oker (Goslar)|Oker]]]]
[[File:BS.Floss.jpg|thumb|Raft on the Oker Bypass Channel in Braunschweig]]

From the village of Oker the River Oker flows away in a northeasterly direction to [[Vienenburg]], where it is joined from the south by the [[Radau]] and then from the southeast by the [[Ecker]]. After these two confluences the river continues southeast past the [[Harly Forest]], after which it bends north to flow through [[Schladen]] and [[Wolfenbüttel]] to [[Braunschweig]]. In south Braunschweig the Oker is dammed by the Eisenbüttel Weir. In the ''Bürgerpark'' shortly before Braunschweig's [[old town]] the Oker divides into the western and eastern bypass channels (''Umflutgraben'') which circumnavigate the historic city centre at a slightly higher level. These channels were laid in the 16th century as the external moats of the town's defences. The actual course of the Oker through the centre of the town was covered and, today, runs through pipes emerging again north of the old town. The water level in the city area is controlled by the St. Peter's Gate Weir (''Petritorwehr'') in the western and the "[[Wends]] Weir" (''Wendenwehr'') in the eastern ditch. Following the merger of the two channels northwest of the city centre the Oker runs north of the district of {{ill|Watenbüttel|de}} in a [[culvert]] under the [[Mittelland Canal]] before it is joined by the [[Schunter]] from the east near Groß Schwülper. It then flows down to its mouth into the River [[Aller (Germany)|Aller]], which is located between [[Gifhorn]] and [[Celle]] at [[Müden (Aller)|Müden]].