Irwin Inlet
{{Short description|Inlet on south coast of Western Australia}}
{{Use Australian English|date=December 2013}}
{{Use dmy dates|date=January 2024}}
{{Infobox Australian place|type = other
| name = Irwin Inlet
| state = wa
| image =
| caption =
| lga = Shire of Denmark
| local_map = yes
| zoom = 12
| postcode =
| coordinates = {{coord|34|58|23|S|116|58|28|E|source:enwiki-plaintext-parser|display=title, inline}}
| area =
| elevation =
}}
Irwin Inlet is an inlet in the located on the Great Southern region of Western Australia.
It was also known as Quarram Inlet.{{Citation | author1=Saw, Bert (Herbert Thomas) | title=First train at Quarram Siding on the Denmark to Nornalup Railway, Western Australia | publication-date=1929 | url=https://trove.nla.gov.au/work/234656482 | access-date=12 January 2021}}{{Citation | author1=Brearley, Anne | author2=Ernest Hodgkin Trust for Estuary Education and Research | author3=National Trust of Australia (W.A.) | author4=University of Western Australia Press | title=Ernest Hodgkin's Swanland : estuaries and coastal lagoons of South-western Australia | publication-date=2005 | publisher=University of Western Australia Press for the Ernest Hodgkin Trust for Estuary Education and Research and National Trust of Australia (WA) | isbn=978-1-920694-38-8}}
The inlet receives water from two main sources, Bow River of the north west and Kent River to the north east. The inlet itself discharges into the Southern Ocean via Foul Bay.
The inlet is approximately {{convert|20|km|mi|0}} east of Walpole and {{convert|30|km|mi|0}} west of Denmark. The South Coast Highway is about {{convert|3|km|mi|0}} north of the inlet.
A sandbar across the entrance to the inlet on the ocean side, but this is often breached during the winter. The inlet bisects Peaceful Bay beach.
The inlet is a wave dominated estuary with a total area of {{convert|13|km2|sqmi|0}}; it is estimated that 30% of the catchment is cleared.{{cite web|url=http://dbforms.ga.gov.au/pls/www/npm.ozest.show_mm?pBlobno=9300|title=Estuary Assessment framework for non-pristine estuaries - Estuary 645 (Irwin Inlet)|year=2009|accessdate=8 March 2009|archive-url=https://web.archive.org/web/20090523092054/http://dbforms.ga.gov.au/pls/www/npm.ozest.show_mm?pBlobno=9300|archive-date=23 May 2009|url-status=dead}}
The inlet is slowly turning into swampland as a result of its high sediment loading and shallow depth. The basin supports large seagrass meadows and is used as a commercial fishery.{{cite web|url=http://www.rivercare.southcoastwa.org.au/infodata/kentc/irwini/irwin.html|title=South Coast Rivercare - Irwin Inlet|year=2004|accessdate=8 March 2009}}
The Bibbulmun Track crosses Irwin Inlet, and canoes are provided in sheds on either side of the track for hikers to make the crossing with. The channel is {{convert|150|m|ft|0}} wide at the point where it must be crossed.{{cite web|url=http://www.bibbulmuntrack.org.au/trip-planner/Track-Towns/Peaceful-Bay.aspx|title=Peaceful Bay - Bibbulmun Track Foundation|year=2009|accessdate=8 March 2009}}