River Eau
{{Short description|River in Lincolnshire, England}}
{{about||other rivers|Barlings Eau|and|Bourne Eau}}
{{Use dmy dates|date=September 2017}}
{{Use British English|date=September 2017}}
{{Infobox river
| name = River Eau
| native_name =
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| image = The River Eau, Scotter - geograph.org.uk - 970226.jpg
| image_size =
| image_caption = River Eau, Scotter
| map =
| map_size =
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| pushpin_map =
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| subdivision_type1 = Country
| subdivision_name1 = England
| subdivision_type2 =
| subdivision_name2 =
| subdivision_type3 = Counties
| subdivision_name3 = Lincolnshire
| subdivision_type4 =
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| length_km = 24
| width_min =
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| discharge1_location =
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| source1 =
| source1_location = Harpswell, Lincolnshire
| source1_coordinates = {{coord|53.39869|-0.60630|display=inline}}
| source1_elevation =
| mouth =
| mouth_location = Susworth, Lincolnshire
| mouth_coordinates = {{coord|53.519612|-0.738527|display=inline,title}}
| mouth_elevation =
| progression =
| river_system =
| basin_size_km2 = 125
| tributaries_left = Northorpe Beck
| tributaries_right = Dar Beck, Manton Sewer
| custom_label =
| custom_data =
| extra = Progression : Eau—Trent—Humber
}}
{{Location map+ |Lincolnshire
|relief = 1
|caption= Map showing the location of Scotter, Source and Outfall to the Trent within Lincolnshire
| places =
{{Location map~ |Lincolnshire
| label = Outfall
| background = darkseagreen
| lat = 53.52
| long = -0.738
| position = left
}}
{{Location map~ |Lincolnshire
| label = Source
| background = darkseagreen
| lat = 53.39
| long = -0.606
}}
{{Location map~ | Lincolnshire
| label = Scotter | background = darkseagreen
|lat = 53.49
|long = -0.66
}}
|float = right
|background = white
|width = 260
}}
The River Eau ({{IPAc-en|j|uː}} {{respell|YOO}}) is a {{convert|15|mi|km|adj=mid|-long}} tributary of the River Trent that flows through Lincolnshire, England.
The Eau catchment lies between that of the Bottesford Beck to the north, and the River Witham to the south and east, and covers an area of {{convert|125|km2|mi2|abbr=off}}. The river is one of the few notable streams that drain the right bank of the tidal Trent.{{cite book|last=Ordnance Survey|title=Scunthorpe and Gainsborough|publisher=Ordnance Survey|year=2002|series=OS Landranger Map Series 112|isbn=0-319-22712-X}}
The source of the river is near Harpswell, at the foot of the Lincolnshire Edge, and it joins the tidal River Trent at Susworth. Unlike other rivers that drain into the tidal Trent, there is no pumping station associated with the outfall, it relies on gravity to discharge during periods of tidal low water.{{cite web|url=http://parishes.lincolnshire.gov.uk/Files/Parish/15/FloodProtectionReportSept09.pdf
|title=Scotter flood protection report |publisher=lincolnshire.gov.uk |date=13 March 2009 |accessdate=20 February 2013}}
The Eau flows through the village of Scotter, which has a history of being flooded by the river; the most recent occasion was in June 2007.
The river is also important for the drainage of the flat low-lying agricultural land that surrounds it, with some 2000 hectares or {{convert|20|km2|mi2|abbr=off}} of the Gainsborough Internal Drainage Board district, relying on the Eau for this function.{{cite web|title=Gainsborough IDB|url=http://www.gidb.co.uk|accessdate=27 February 2013|url-status=dead|archiveurl=https://web.archive.org/web/20080117224018/http://www.gidb.co.uk/|archivedate=17 January 2008|df=dmy-all}} Whilst the drains that discharge into the Eau are maintained by the Drainage Board, the river is the responsibility of the Environment Agency being designated as a Main river.{{cite web|url=http://maps.environment-agency.gov.uk/wiyby/wiybyController?x=357683.0&y=355134.0&scale=1&layerGroups=default&ep=map&textonly=off&lang=_e&topic=floodmap#x=486932&y=398519&lg=1,&scale=7|title=Environment Agency What's in your Backyard |publisher=Environment-agency.gov.uk |accessdate= 10 May 2013}}
Its tributaries are Northorpe Beck, Manton Sewer and Dar Beck.Ordnance Survey, 1:25,000 Scale Colour Raster map
