Editing Oker

{{Short description|River in Germany}}
{{about|the river|the hamlet in England|Oker, Derbyshire|the Goslar borough|Oker (Goslar)}}
{{Infobox river
  | name              = Oker
  | image             = PICT4952_Okermündung_in_Müden.JPG
  | image_caption     = Confluence of the Oker and Aller near Müden
  | source1_location  = [[Harz Mountains]]
  | source1_coordinates= {{coord|51|46|42|N|10|29|29|E|region:DE-NI}}
  | mouth_location    = [[Aller (Germany)|Aller]]
  | mouth_coordinates = {{coord|52|31|26|N|10|21|39|E|display=inline,title}}
  | progression       = {{RAller}}
  | subdivision_type1 = Country
  | subdivision_name1 = [[Germany]]
  | length_km = 128.2
  | length_ref = {{GeoQuelle|DE-NI|UK}}
  | source1_elevation = {{convert|900|m|ft}}
  | discharge1_avg    =
  | basin_size_km2 = 1822
  | basin_size_ref = {{GeoQuelle|DE-NI|UK}}
}}
The '''Oker''' ({{IPA|de|ˈoːkɐ|pron}}) is a [[river]] in [[Lower Saxony]], [[Germany]], that has historically formed an important political boundary. It is a left tributary of the River [[Aller (Germany)|Aller]], {{convert|128|km|mi}} in length and runs in a generally northerly direction.

== Origin and meaning of the name ==
The river's name was recorded around 830 as ''Obacra'' and, later, as ''Ovokare'' und ''Ovakara''.<ref name="Blume">H. Blume: ''Oker, Schunter, Wabe.'' In: ''Braunschweigisches Jahrbuch für Landesgeschichte'', vol. 86, 2005, p. 14 sqq.</ref> The origin of the name is derived from the [[root (linguistics)|root]]s ''ov-'' and ''-akara'' meaning “upper” (cf. [[New High German]] ''ober-'') and  “onward rushing” (rendered in German as “Vorwärtsdrängende”) <ref name="Blume"/> as distinct from its tributary, the [[Ecker]], whose name means only “onward rushing”.

== 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]].

== The Oker as border river ==
[[File:SchunterMuendung.jpg|thumb|Mouth of the Schunter into the Oker near Groß Schwülper]]

Since the early ninth century the middle Oker river has formed the [[Diocese|diocesan]] boundary between the [[Bishopric of Halberstadt|bishoprics of Halberstadt]] and [[Roman Catholic Diocese of Hildesheim|Hildesheim]], established by Emperor [[Charlemagne]] and his son [[Louis the Pious]] in the [[Duchy of Saxony]]. North of Schladen the royal palace (''[[Königspfalz]]'') of [[Schladen-Werla|Werla]] was established on the banks about {{convert|20|m}} above the river bed. From the High Middle Ages the Oker between the villages of [[Ohrum]] and [[Börßum]] formed the eastern boundary of the [[Prince-Bishopric of Hildesheim]] with the [[Principality of Brunswick-Wolfenbüttel|Duchy of Brunswick-Wolfenbüttel]], and further south to Wiedelah (today part of [[Vienenburg]]) with the Prince-Bishopric of Halberstadt, which became the Prussian [[Principality of Halberstadt]] following its [[secularization]] in 1648.

The Bishopric of Halberstadt was likewise [[German Mediatisation|mediatised]] in 1803, and according to the Final Act of the 1815 [[Vienna Congress]], the Oker was the eastern border of the [[Kingdom of Hanover]] with the [[Duchy of Brunswick]] and the Prussian [[Province of Saxony]]. When the [[Kingdom of Prussia]] annexed Hanover in 1866, it became the inner Prussian border between the [[Province of Hanover|provinces of Hanover]] and [[Province of Saxony|Saxony]] as well as the border, north of Börßum to Ohrum between the Province of Hanover in the west and the Duchy of Brunswick in the east. From 1945 to 1990 the [[Inner German border]] between [[East Germany|East]] and [[West Germany]] ran down the centre of the Oker between Wiedelah and Schladen, today between the German [[States of Germany|states]] of [[Saxony-Anhalt]] and [[Lower Saxony]].

Since the [[Expo 2000]] bridges over the Oker in Braunschweig and its surrounding area were artistically designed; after 2004 this was carried out as part of the ''Okerlicht'' project.

==Tributaries==
{|
| valign="top" |
Left tributaries (from source to mouth):
* Lange
* [[Abzucht]]
* [[Ohebach (Oker)|Ohebach]]
* {{ill|Weddebach|ceb||de}}
* [[Warne (river)|Warne]]
* {{ill|Brückenbach|de|Brückenbach (Oker)}}
* {{ill|Thiedebach|de}}
| valign="top" |
Right tributaries:
* {{ill|Hurlebach|de}}
* [[Radau]]
* [[Ecker]]
* [[Ilse (river)|Ilse]]
* [[Altenau (Oker)|Altenau]]
* [[Schunter]]
* [[Bickgraben]]
|}

==See also==
*[[List of rivers of Lower Saxony]]

== References ==
{{Reflist}}

== External links ==
{{Commons category|Oker (Aller)|Oker}}
* [http://www.geoberg.de/text/mining/09022401.php Heavy metal pollution of the Oker] {{in lang|de}}
* [http://www.rainriders.de Description of white water canoe section between Kraftwerk and Nachstaubecken with many photos] {{Webarchive|url=https://web.archive.org/web/20201202023500/http://www.rainriders.de/ |date=2020-12-02 }} {{in lang|de}}

==See also==
[[Oste class fleet service ship]]

{{Authority control}}

[[Category:Oker basin| ]]
[[Category:Rivers of Lower Saxony]]
[[Category:Rivers of the Harz]]
[[Category:Rivers of Germany]]