:River Trothy

{{Short description|River in Wales}}

{{more citations needed|date=February 2024}}

{{Use dmy dates|date=April 2025}}

{{Use British English|date=January 2018}}

{{Infobox river

| name = Trothy

| native_name = {{nativename|cy|Troddi}}

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| image = Afon Troddi-River Trothy - geograph.org.uk - 606762.jpg

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| image_caption = The River Trothy near Monmouth

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| subdivision_type1 = Country

| subdivision_name1 = Wales

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| subdivision_type3 = Region

| subdivision_name3 = Monmouthshire

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| source1_location = Monmouthshire, Wales

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| mouth = River Wye

| mouth_location = Monmouth, Wales

| mouth_coordinates = {{coord|51|48|4.3|N|2|42|12.8|W|display=title,inline|region:GB_type:river_source:GNS-enwiki}}

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The River Trothy ({{langx|cy|Afon Troddi}}) is a river which flows through north Monmouthshire, in rural south east Wales. It is a tributary of the River Wye.{{cite news |last1=Capurro |first1=Daniel |title=A key tributary to 'dying' River Wye has pollution levels 175 per cent above official targets |url=https://inews.co.uk/news/environment/dying-river-wye-tributary-pollution-levels-2620295 |access-date=4 February 2024 |work=inews.co.uk |date=15 September 2023 |language=en}}{{cite web |last1=Lewis |first1=Vaughan |title=Habitat advisory visit to the River Trothy, Monmouth, Wales |url=https://www.wildtrout.org/assets/reports/2006trothy.pdf |publisher=Wild Trout Trust |access-date=4 February 2024}}

The river rises on Campston Hill, northeast of Abergavenny. It flows southwards until Llanvapley, where it turns east. About {{convert|1/3|mi}} south of Monmouth the river joins the confluence of the River Wye and the River Monnow.