River Aller

{{Short description|River in Somerset, England}}

{{About||the main tributary of the Weser in North Germany|Aller (Germany)|the river in Asturias|Aller (Asturian river)}}

{{Use dmy dates|date=April 2022}}

{{Infobox river

| name = River Aller

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| image = Allerford bridge.jpg

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| image_caption = Packhorse Bridge, Allerford

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| subdivision_type1 = Country

| subdivision_name1 = England

| subdivision_type2 = State

| subdivision_name2 = Somerset

| subdivision_type3 = Region

| subdivision_name3 = Exmoor

| subdivision_type4 = District

| subdivision_name4 = West Somerset

| subdivision_type5 = City

| subdivision_name5 = Allerford

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| source1_location = Holnicote, West Somerset

| source1_coordinates= {{coord|51|11|54|N|3|32|52|W|display=inline}}

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| mouth = River Horner

| mouth_location = near Bossington, Somerset

| mouth_coordinates = {{coord|51|13|12|N|3|34|38|W|display=inline,title}}

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The River Aller is a small river on Exmoor in Somerset, England.

It rises as several small streams around Tivington and Huntscott and flows through the Holnicote Estate passing Holnicote and through Allerford, where it passes under a packhorse bridge of medieval origin.{{cite web | title=Packhorse Bridge | work=historicengland.org.uk | url=https://historicengland.org.uk/listing/the-list/list-entry/1058014 | access-date=2008-01-05}} It then joins the River Horner, which flows into Porlock Bay near Hurlstone Point on the Bristol Channel.{{cite web|title=River Aller|url=http://somersetrivers.org/index.php?module=Content&func=view&pid=2|publisher=Somerset Rivers|access-date=23 September 2012}}

Because of the surrounding geology the area has been at risk of flooding. To help manage this risk telemetry monitoring of flows and a siren warning system have been proposed.{{cite web|title=West Somerset Catchment Flood Management Plan |url=http://www.environment-agency.gov.uk/static/documents/Leisure/_CFMP_WestSomerset_2012.pdf |format=PDF |page=12 |publisher=Environment Agency |access-date=23 September 2012 |url-status=dead |archive-url=https://web.archive.org/web/20121217054043/http://environment-agency.gov.uk/static/documents/Leisure/_CFMP_WestSomerset_2012.pdf |archive-date=17 December 2012 }}