View source for Avon River (Nova Scotia)

{{Infobox river
| name              = Avon River 
| image             = File:Land of Evangeline, Dominion Atlantic Railway (1897) (14586291188).jpg
| image_caption     = 19th-century photograph of the [[Dominion Atlantic Railway]] bridge at [[Windsor, Nova Scotia|Windsor]]
| subdivision_type1 = Country
| subdivision_name1 = [[Canada]]
| subdivision_type2 = [[Provinces and territories of Canada|Province]]
| subdivision_name2 = [[Nova Scotia]]
| source1_location  = 
| mouth_location    = [[Minas Basin]]
|length_km=64
| source1_elevation = 
| mouth_elevation   = [[sea level]] 
| discharge1_avg    = 
|basin_size_km2=1,306
}}__NOTOC__
The '''Avon River''' is a small [[river]] in central [[Nova Scotia]], Canada.

A northerly flowing river, the Avon River's flow rises at an elevation of 145 metres (475&nbsp;ft.) at Card and Bag Lakes on the [[South Mountain (Nova Scotia)|South Mountain]], a distance of approximately 29 kilometres (18 miles) southwest of the town of [[Windsor, Nova Scotia|Windsor]]. Its [[meander]] length is {{convert|64|km|mi|abbr=on}}.<ref>[http://reference.allrefer.com/gazetteer/A/A08881-avon-river.html ''North American Gazetteer''] {{webarchive |url=https://web.archive.org/web/20060106192606/http://reference.allrefer.com/gazetteer/A/A08881-avon-river.html |date=January 6, 2006 }}</ref>  At Windsor Forks, the West Branch Avon River (the main tributary) and the Southwest Branch Avon add their flow to the Avon.  The West Branch Avon River rises at an elevation of 175 metres (574&nbsp;ft.) at Black River Lake.  Both the flows of the Avon and the West Branch have been impeded by hydropower developments in the early twentieth century. Near the rural community of [[Martock, Nova Scotia|Martock]], the river enters a broad glacial river valley forming a [[ria]]<ref>[http://museum.gov.ns.ca/mnh/nature/nhns2/500/fig16.htm Schematic drawing and description] {{webarchive |url=https://web.archive.org/web/20060927072932/http://museum.gov.ns.ca/mnh/nature/nhns2/500/fig16.htm |date=September 27, 2006 }}</ref> where it becomes [[tide|tidal]], creating an [[estuary]] for its remaining route to the [[Minas Basin]] at Kempt Shore,<ref>{{cite web | url=https://en.wikipedia.org/wiki/Kempt_Shore,_Nova_Scotia | title=Kempt Shore, Nova Scotia }}</ref>{{Circular reference|date=September 2022}} several kilometres downriver from the town of [[Hantsport, Nova Scotia|Hantsport]]. Another tributary, the [[St. Croix River (Nova Scotia)|St. Croix River]] joins just below Windsor creating a total watershed of 1,306 square kilometres.<ref>[http://ojs.library.dal.ca/NSM/issue/view/349 ''Natural History of Nova Scotia, Volume 1'', Chapter T8 "Freshwater Hydrology", Nova Scotia Museum (1996) p.152]</ref>

Rivers flowing into the Avon include the [[Halfway River, Kings County, Nova Scotia|Halfway]], Herbert, Cogmagun, [[Kennetcook River|Kennetcook]] and [[St. Croix River (Nova Scotia)|St. Croix]].

The Avon River is evident on many very early maps of the region and by 1686 is shown, along with its [[drainage basin]], on [[Jean-Baptiste-Louis Franquelin]]'s map in great detail.

==Causeway and controversy==
{{More citations needed|section|date=July 2021}}
In 1970 the Avon River was completely obstructed by a rock and earth fill [[causeway]] immediately downstream from Windsor at its junction with the [[St. Croix River (Nova Scotia)|St. Croix River]] as part of the development of a controlled access expressway called [[Nova Scotia Highway 101|Highway 101]].

The Avon River Causeway replaced an existing road bridge upriver from town and also resulted in the rerouting of the [[Dominion Atlantic Railway]]'s [[Halifax Regional Municipality|Halifax]]-[[Yarmouth, Nova Scotia|Yarmouth]] main line which used to run through Windsor's downtown, crossing the river on a bridge parallel to the road bridge immediately upriver from the town.

The causeway controls the Avon River's discharge and the incoming tidal waters of the Minas Basin through a series of flood control gates which are intended to regulate the river's flowage to prevent flooding of agricultural lands upriver near Martock. The section of the Avon River upriver of the causeway along the Windsor waterfront is now a 'man-made' freshwater, Lake Pesaquid.

The construction of the causeway has dramatically affected the Avon River downstream from Windsor, with large parts of the once-navigable river now being obstructed by large mud flats and vegetation, owing to the lack of tidal exchange and freshwater discharge. The nature writer [[Harry Thurston]] has noted, "Almost before the last stone was put in place, sediment began to accumulate to an alarming rate - 5 to 14 centimetres per month. Within seven years, a four metre high island of silt formed on the seaward side of the causeway; and the effects were felt 20 kilometres downstream, where two metres of mud impaired navigation at Hantsport."<ref name=Thurston>[[Harry Thurston]], ''Tidal Life: A Natural History of the Bay of Fundy''. Camden House Publishing, 1990</ref>{{rp|p43}}

Dr. Michael Risk of the University of Guelph, researching the build-up of a new mud flat on the seaward side of the causeway, "estimated that the bottom-dwelling creatures at Windsor were experiencing a two-thirds mortality rate", which led him to state the new formation was a "biological [[desert]]". The onset of the mud flat formation left the sediments in an initial state which were too soft to support organisms. The need to monitor and assess the impacts of such changes gave impetus to a greater interest in [[Bay of Fundy]] ecosystem and the ultimate establishment of the Acadia Centre for Estuarine Research (ACER) in Wolfville.  Contrasting the initial decline of bottom-dwelling creatures, Dr. Graham Daborn of ACER found that zoo-plankton "are more abundant than previously thought. They appear to be able to thrive on non-living organic matter..." and that this "abundance of creatures at the lower end of the food chain suggests a considerable nursery role for the inner Bay."  This notion is supported by research work completed by Dr. Sherman Bleakney of Acadia University.<ref name=Thurston/>{{rp|p43-44}}

Recently announced plans for the expansion of Highway 101 between the [[Halifax Regional Municipality]] and the eastern end of the [[Annapolis Valley]] have raised concerns about maintaining the Avon River causeway. An environmental lobby group, Friends of the Avon River (FAR), has called upon the Federal Fisheries Ministers to instigate a Comprehensive Environmental Impact Assessment Study (CEIA) of the complete Avon River Watershed in order to protect the Endangered Atlantic Salmon, the COSWIC listed American Eel and their 'critical habitats'. The Avon River Causeway has 'zero' fish passageway. Thus, impeding all fish species needing to migrate to their freshwater habitats, in order to complete their lifecycles.  FAR reviewed and supported a report to have a more in-depth study regarding the protection of fish species before the expansion of gypsum quarries within the river's watershed because of threats to river life, citing the use de-watering runoff from the quarries.<ref>[http://www.avondalemedia.ca/APWPS/releases/far.php FAR Press Release]{{dead link|date=October 2016 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

A decision in August 2007 by the [[New Brunswick]] government to remove a similar causeway (constructed in 1968) blocking the [[Petitcodiac River]], another tributary of the Bay of Fundy, to avoid facing charges under the federal ''Fisheries Act'', is expected to have ramifications for the Avon River causeway.

==See also==
*[[List of rivers of Nova Scotia]]

==References==
{{Reflist|2}}

==Further reading==
* Danika van Proosdij and Sarah M. Townsend, [https://web.archive.org/web/20110706174832/http://docs.informatics.management.dal.ca/gsdl/collect/bofep1/pdf/WF/BOFEP6-2004-258.pdf "Sedimentation and Mechanisms of Salt Marsh Colonization on the Windsor Mudflats"], in ''The Changing Bay of Fundy—Beyond 400 Years'', 2004
* J.A. Percy, [http://www.bofep.org/PDFfiles/fundy_issue_28.pdf "The ‘Cause’ in Causeway: Crossing the Avon River at Windsor"], ''Fundy Issues #28'' newsletter of the Bay of Fundy Ecosystem Partnership (BOFEP), Winter 2008.

==External links==
* [https://web.archive.org/web/20061230201233/http://gov.ns.ca/tran/publications/ACER75_Env%20Implications%20of%20Causeway%20Expansion.pdf 2004 study of environmental impacts of widening the causeway]
* [https://web.archive.org/web/20080408162537/http://ace.acadiau.ca/science/cer/index.htm Acadia Centre for Estuarine Research]

{{coord|44|59|21.35|N|64|9|7.29|W|region:CA-NS_type:river|display=title}}
{{Rivers of Nova Scotia}}

{{authority control}}

[[Category:Landforms of Hants County, Nova Scotia]]
[[Category:Rivers of Nova Scotia]]