Editing River Parrett (section)

== Course ==
The River Parrett is {{convert|37|mi|km|0}} long, flowing roughly south to north from [[Dorset]] through Somerset. Its [[River source|source]] is in the Thorney Mills [[Spring (hydrology)|springs]] in the hills around [[Chedington]],<ref>{{harvnb|OS 193|2008|loc=section 48 05}}</ref><ref>{{cite web|title=River Parrett|url=http://somersetrivers.org/index.php?module=Content&func=view&pid=19|publisher=Somerset Rivers |access-date=11 May 2015 |url-status=live |archive-url=https://web.archive.org/web/20150909004707/http://somersetrivers.org/index.php?module=Content&func=view&pid=19 |archive-date= 9 September 2015}}</ref> {{convert|2.5|mi|km|0}} from that of the [[River Axe (Lyme Bay)|River Axe]], in nearby [[Beaminster]], which runs in the opposite direction to the [[English Channel]] at [[Axmouth]] in Devon. The two rivers give their names to Parrett and Axe Parish Council.<ref>{{cite web|url=http://www.parrettandaxe.org.uk/|title=Welcome to Parrett & Axe Parish Council|publisher=Parrett & Axe Parish Council |access-date=18 March 2010 |url-status=usurped |archive-url=https://web.archive.org/web/20101211172258/http://www.parrettandaxe.org.uk/ |archive-date=11 December 2010}}</ref>

From its source, the Parrett runs north through [[South Perrott]] and under the [[West of England Main Line|Salisbury to Exeter railway line]] before passing to the west of [[North Perrott]] and [[Haselbury Plucknett]].<ref name=trail>''The River Parrett Trail&nbsp;– Following a river from source to mouth'', (1997), Tourism and Marketing Unit, South Somerset District Council</ref> It then runs through fields between [[Merriott]] to the west and [[West Chinnock]] and [[Chiselborough]] to the east. Passing under the [[A303 road]] to the east of [[South Petherton]], the river flows between [[East Lambrook]] and [[Bower Hinton]] west of [[Martock]] and then towards [[Kingsbury Episcopi]], through [[Thorney, Somerset|Thorney]] and [[Muchelney]], passing the remains of [[Muchelney Abbey]] before entering [[Langport]], which is about {{convert|10|mi|km}} north of Chiselborough. Below Thorney Bridge the river's banks have been raised to mitigate flooding.<ref name=trail/>

[[File:River Parrett.jpg|left|thumb|280px|Aerial view of the mouth of the River Parrett as it flows into [[Bridgwater Bay]]]]
The Parrett then flows northwest for approximately another {{convert|10|mi|km}} to Bridgwater through the [[Somerset Levels]] past [[Aller, Somerset|Aller]], close to the [[Aller and Beer Woods]] and [[Aller Hill]] [[Site of Special Scientific Interest|biological Sites of Special Scientific Interest]] (SSSI). The sluice gate (formerly a [[Canal lock|lock]] built in the late 1830s) at the [[deserted medieval village]] of Oath marks the river's [[Head of tide|tidal limit]].<ref name="eelodyssey"/><ref name="Paper by the Environment Agency">{{cite web|url=http://www1.somerset.gov.uk/council/board10/2005%20December%2013%20Item%205%20Environment%20Agency%20Paper.htm|title=Paper by the Environment Agency|work=Somerset County Council Scrutiny Committee |publisher=Somerset County Council |access-date=21 December 2009 |url-status=live |archive-url=https://web.archive.org/web/20110717061438/http://www1.somerset.gov.uk/council/board10/2005%20December%2013%20Item%205%20Environment%20Agency%20Paper.htm |archive-date=17 July 2011}}</ref><ref name="hadfield83-91">{{Harvnb|Hadfield|1967|pp=83–91}}</ref> The river then crosses [[Southlake Moor]]. The next major landmark along the river's course is [[Burrow Mump]], an ancient earthwork owned by the [[National Trust for Places of Historic Interest or Natural Beauty|National Trust]].<ref name="curio">{{harvnb|Leete-Hodge|1985|p=82}}</ref> The river then arrives in [[Burrowbridge]], where the old pumping station building was once a museum.<ref name="curio"/> Flowing north, it passes [[Langmead and Weston Level]] SSSI,<ref>{{cite web|title=Langmead and Weston Level |work=Natural England |url=https://designatedsites.naturalengland.org.uk/PDFsForWeb/Citation/1005918.pdf |access-date=17 August 2006 |url-status=live |archive-url=https://web.archive.org/web/20061013121442/http://www.english-nature.org.uk/citation/citation_photo/1005918.pdf |archive-date=13 October 2006 }}</ref> and on past the land-drainage pumping station at [[Westonzoyland Pumping Station Museum|Westonzoyland]].<ref name="westonpump">{{cite web |title=The Westonzoyland Pumping Station |url=http://www.wzlet.org/index.htm |publisher=Westonzoyland pumping station |access-date=11 November 2010 |url-status=dead |archive-url=https://web.archive.org/web/20110206152610/http://www.wzlet.org/index.htm |archive-date=6 February 2011 }}</ref>

Further downstream the river passes the village of [[Huntworth]] before flowing under the [[M5 motorway]] at Dunwear. As it enters Bridgwater it passes under Somerset and Hamp Bridges, and past [[Bridgwater Castle]], which had a tidal [[moat]] up to {{convert|65|ft|m|0}} wide in places, fed by water from the river.<ref>{{cite web|url=http://www.bridgwater.net/Town/About_Town/History/bridgwater_castle.htm |title=Bridgwater Castle |publisher=Bridgwater.net |access-date=12 October 2008 |url-status=dead |archive-url=https://web.archive.org/web/20080515134201/http://www.bridgwater.net/Town/About_Town/History/bridgwater_castle.htm |archive-date=15 May 2008 }}</ref> From Bridgwater to the sea is approximately {{convert|6|mi|km}}. The [[King's Sedgemoor Drain]] empties into the River Parrett next to the wharf at Dunball; it enters via a [[Sluice|clyce]] (or clyse), which is a local word for a sluice. The clyce has been moved about {{convert|0.3|mi|m|sigfig=1}} downstream from its original position and now obstructs the entrance to the small harbour next to the wharf.<ref name="otter">{{harvnb|Otter|1994|pp=94–100}}</ref>

[[File:River Parrett near Pawlett.jpg|alt=River flowing around a bend with a muddy bank on the left. Beyond the river are white concrete block buildings and multiple electricity pylons.|thumb|The river near [[Pawlett]] showing [[Hinkley Point]] power stations [[Hinkley Point A nuclear power station|A]] and [[Hinkley Point B nuclear power station|B]]]]
The course of the river below Bridgwater is now somewhat straighter than in former times. The village of [[Combwich]] lies adjacent to a channel in the river known as "Combwich Reach"; from here the Parrett flows to the [[Bristol Channel]] past the [[Steart Peninsula]]. [[Cartography|Cartographic]] evidence indicates that in the early 18th century the peninsula was longer than at present.<ref name="mcdonnell">{{cite journal |editor=Bell, Martin |journal=Archaeology in the Severn Estuary: Annual Report |year=1995 |volume= 6 |publisher=Severn Estuary Levels Research Committee |last=McDonnell |first=Richard |title=Island evolution in Bridgwater bay and the Parrett Estuary: an historical geography |pages=71–83}}</ref> A "neck" started to form in the peninsula, and by 1802 the tip had broken off to form [[Stert Island]].<ref name="mcdonnell"/> Fenning Island also broke away but has rejoined the peninsula.<ref name="mcdonnell"/> Much of the peninsula's northern end eroded away or now exists as "islands" visible at low tide within an [[Intertidal zone|intertidal]] area of mud known as the Stert Flats.<ref name="mcdonnell"/>

The mouth at [[Burnham-on-Sea]] is a [[National nature reserves in England|nature reserve]] where the river flows into [[Bridgwater Bay]] on the Bristol Channel. In addition to the rivers Parrett, [[River Brue|Brue]] and [[Washford River|Washford]], several of the man-made drainage ditches, including the [[River Huntspill]] from the Somerset Levels, and the Cannington Brook from the "[[Pawlett, Somerset|Pawlett]] Hams", also discharge into the bay.<ref name=sssicitation/>

=== Flow and tidal bore ===
The Parrett has only one gauging station, at Chiselborough, fairly close to the source. It measures flow from the first {{convert|29|sqmi}} of the [[drainage basin]], or about 4.3&nbsp;per cent of the total. The mean flow measured by the [[Environment Agency]] at Chiselborough was {{convert|1.19|m3/s|cuft/s|order=flip}}, with a peak of {{convert|173|m3/s|cuft/s|order=flip}} on 30 May 1979 and a minimum of {{convert|0.07|m3/s|cuft/s|order=flip}} over a seven-day period in August 1976. Tributaries of the Parrett with gauging stations include the Yeo, Isle, Cary, and Tone.<ref name="hydoreg">{{harvnb|Marsh|Hannaford|2008|p=128}}</ref>

The lower Parrett has a fall of only {{convert|1|ft/mi|m/km|1}} between Langport and Bridgwater.<ref name="edpack">{{cite web|url=http://www.southsomerset.gov.uk/media/90305/langport_and_river_parrett_education_pack.pdf |title=River Parrett Trail |access-date=11 May 2015  |work=Langport & River Parrett Visitor Centre |url-status=dead |archive-url=https://web.archive.org/web/20151223181437/http://www.southsomerset.gov.uk/media/90305/langport_and_river_parrett_education_pack.pdf |archive-date=23 December 2015}}</ref> To the northeast of the River Parrett's mouth, the Bristol Channel becomes the [[Severn Estuary]], which has a [[tidal range]] of {{convert|14|m|ft}}.<ref>{{cite web|url=http://www.severnestuary.net/sep/pdfs/barker_06_final_project_report.pdf |title=Managing Tidal Change Natasha Barker Winston Churchill Memorial Trust Travelling Fellowship Award 2006 Final Project Report |last=Barker |first=Natasha |date=March 2008 |work=Winston Churchill Memorial Trust Travelling Fellowship Award 2006 |publisher=Severn Estuary Partnership |pages=8 |access-date=8 May 2010 |url-status=dead |archive-url=https://web.archive.org/web/20110723014623/http://www.severnestuary.net/sep/pdfs/barker_06_final_project_report.pdf |archive-date=23 July 2011}}</ref> The rate and direction of flow of the Parrett is therefore dependent on the state of the tide on the [[River Severn]]. In common with the lower reaches of the River Severn, the Parrett experiences a [[tidal bore]]. Certain combinations of the tides funnel the rising water into a wave that travels upstream at about {{convert|6|mph|km/h|0}}, against the river's current.<ref>{{cite web|url=http://www.bridgwatertowncouncil.gov.uk/history/river-and-shipping/the-docks/|last=Evans |first=Roger |title=The Docks |work=History |publisher=Bridgwater Somerset. info |access-date=11 May 2015 |url-status=live |archive-url=https://web.archive.org/web/20150518095848/http://www.bridgwatertowncouncil.gov.uk/history/river-and-shipping/the-docks/ |archive-date=18 May 2015}}</ref>

===Hydrology and water quality===
Near the source at Chiselborough the typical level range for the depth of the river is {{convert|0.05|m}} to {{convert|0.63|m}} but has reached a maximum of {{convert|2.93|m}}.<ref>{{cite web|title=River Parrett at Chiselborough|url=http://apps.environment-agency.gov.uk/river-and-sea-levels/120716.aspx?stationId=3075|website=River and Sea Levels |publisher=Environment Agency |access-date=19 June 2015 |url-status=live |archive-url=https://web.archive.org/web/20150619203447/http://apps.environment-agency.gov.uk/river-and-sea-levels/120716.aspx?stationId=3075 |archive-date=19 June 2015}}</ref> The mean flow rate is {{convert|1.196|m3/s}}.<ref>{{cite web|title=52007 – Parrett at Chiselborough |url=http://www.ceh.ac.uk/data/nrfa/data/meanflow.html?52007 |publisher=Centre for Ecology and Hydrology |access-date=19 June 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150619195737/http://www.ceh.ac.uk/data/nrfa/data/meanflow.html?52007 |archive-date=19 June 2015}}</ref> By the time it reaches Gaw Bridge the normal level range is {{convert|0.23|m}} to {{convert|0.97|m}} and a highest reading of {{convert|3.84|m}}.<ref>{{cite web|title=River Parrett at Gaw Bridge|url=http://apps.environment-agency.gov.uk/river-and-sea-levels/120716.aspx?stationId=3072|website=River and Sea Levels |publisher=Environment Agency |access-date=19 June 2015 |url-status=live |archive-url=https://web.archive.org/web/20150619204640/http://apps.environment-agency.gov.uk/river-and-sea-levels/120716.aspx?stationId=3072 |archive-date=19 June 2015}}</ref> At West Quay in Bridgwater where the river is tidal the highest astronomical tide level is {{convert|8.63|m}} above [[ordnance datum]] (AOD).<ref>{{cite web|title=River Parrett (Tidal) at West Quay|url=http://apps.environment-agency.gov.uk/river-and-sea-levels/120716.aspx?stationId=3067|website=River and Sea Levels |publisher=Environment Agency |access-date=19 June 2015 |url-status=live |archive-url=https://web.archive.org/web/20150619204128/http://apps.environment-agency.gov.uk/river-and-sea-levels/120716.aspx?stationId=3067 |archive-date=19 June 2015}}</ref>

For the purpose of water quality measurement, the river is divided into five water body areas by the [[Environment Agency]]. In 2015, both the area from the source to Broad River around Crewkerne and the area from Broad River to Lopen Brook are rated good for chemical quality and moderate for ecological quality.<ref>{{cite web|title=Parrett&nbsp;– headwaters to Broad River|url=http://environment.data.gov.uk/catchment-planning/WaterBody/GB108052015260|website=Catchment Data Explorer|publisher=Environment Agency|access-date=19 June 2015}}</ref><ref>{{cite web|title=Parrett&nbsp;– Broad River to Lopen Bk|url=http://environment.data.gov.uk/catchment-planning/WaterBody/GB108052015321|website=Catchment Data Explorer|publisher=Environment Agency|access-date=19 June 2015}}</ref> The area from Lopen Brook to the River Isle, around Martock and South Petherton, is rated good for chemical quality, poor for ecological quality and poor overall.<ref>{{cite web|title=Parrett&nbsp;– Lopen Bk to R Isle|url=http://environment.data.gov.uk/catchment-planning/WaterBody/GB108052015360|website=Catchment Data Explorer|publisher=Environment Agency|access-date=19 June 2015}}</ref> From the River Isle to River Yeo around Muchelney, chemical quality is rated good, and ecology is rated moderate.<ref>{{cite web|title=Parrett&nbsp;– R Isle to R Yeo|url=http://environment.data.gov.uk/catchment-planning/WaterBody/GB108052015370|website=Catchment Data Explorer|publisher=Environment Agency|access-date=19 June 2015}}</ref> The section around Langport to the West Sedgemoor Drain continues to rate good for chemical quality and moderate for ecological quality,<ref>{{cite web|title=Parrett&nbsp;– R Yeo to West Sedgemoor Drain|url=http://environment.data.gov.uk/catchment-planning/WaterBody/GB108052015470|website=Catchment Data Explorer|publisher=Environment Agency|access-date=19 June 2015}}</ref> as does the final area leading to Bridgwater Bay.<ref>{{cite web|title=Parrett|url=http://environment.data.gov.uk/catchment-planning/WaterBody/GB540805210900|website=Catchment Data Explorer|publisher=Environment Agency|access-date=19 June 2015}}</ref>