Loch Calder
{{Use dmy dates|date=April 2022}}
{{Infobox body of water
| name = Loch Calder
| other_name =
| image = Loch Calder - geograph.org.uk - 172732.jpg
| alt = Loch Calder looking west
| caption =
| image_bathymetry =
|pushpin_map=Scotland Highland
| caption_bathymetry =
| location = Caithness, Highland, Scotland
| coords = {{coord|58.516667|N|3.583333|W|region:GB-ORK_type:waterbody_source:GNS-enwiki|display=inline,title}}{{cite web |url=http://www.britishlakes.info/2358-loch-calder-highland|title=Loch Calder|author= |website=British lakes |publisher=British Lakes|accessdate=12 June 2016}}
| type = freshwater loch
| inflow =Loch Olginey{{cite web |url=http://www.scottish-places.info/features/featurefirst2217.html|title=Loch Calder|website=The Gazetteer for Scotland|accessdate=12 June 2016}}
| catchment =
| basin_countries = Scotland
| length = {{convert|5|mi|km|abbr=on}}{{cite web |url=http://maps.nls.uk/bathymetric/text.cfm?seq=1299|title=Bathymetrical Survey of the Fresh-Water Lochs of Scotland, 1897-1909, Lochs of the Forss Basin|website=National Library of Scotland |accessdate=12 June 2016}}
| width = {{convert|1|mi|km|abbr=on}}
| area = {{convert|381.5|ha|acre|abbr=on}}
| depth = {{convert|21|ft|m|abbr=on}}
| max-depth = {{convert|85|ft|m|abbr=on}}
| volume = {{convert|767000000|ft3|m3|abbr=on}}
| residence_time =
| shore = {{convert|12.9|km|mi|abbr=on}}
| elevation = {{convert|66|m|ft|abbr=on}}
| cities =
}}
Loch Calder is a lowland freshwater loch lying approximately {{convert|5|mi|km|abbr=on}} south west of Thurso in the Scottish Highlands. The loch is large with an irregular shape and has perimeter of {{convert|12.8|km|mi|abbr=on}}. It is approximately {{convert|2.33|mi|km|abbr=on}} long, has an average depth of {{convert|21|ft|m|abbr=on}} and is {{convert|85|ft|m|abbr=on}} at its deepest. The loch was surveyed on 6 October 1902 by John Parsons and T.R.H. Garrett and later charted{{cite web|url=http://maps.nls.uk/view/74422297|title=Loch Calder; Loch Shurrery (Vol. 5, Plate 7), Bathymetrical Survey, 1897-1909|website=National Library of Scotland|publisher=|date= |accessdate=12 June 2016}} as part of Sir John Murray's Bathymetrical Survey of Fresh-Water Lochs of Scotland 1897-1909.
Around the loch are several archaeological remains. At the northern end of the loch is Tulach an t'Sionnaich, a well preserved chambered cairn, one of two cairns known as the Tullochs of Assery.{{Cite web|url=https://canmore.org.uk/site/7907/tulloch-of-assery|title=Tulloch Of Assery|website=Canmore|publisher=Historic Environment Scotland|publication-place=Edinburgh|access-date=2016-06-12}} On the eastern shore, near Achavarn, lies the site of a broch, although much of the structure has been removed.{{Cite web|url=https://canmore.org.uk/site/7645/tulloch-of-achavarn|title=Tulloch Of Achavarn|website=Canmore|publisher=Historic Environment Scotland|publication-place=Edinburgh|access-date=2016-06-12}} It is thought that there was an artificial island or crannog near the western shore dating from the 17th century. The island, known as Big Island, may have contained a dwelling which was said to be that of a robber.{{Cite web|url=https://canmore.org.uk/site/7906/big-island-loch-calder|title=Big Island, Loch Calder|website=Canmore|publisher=Historic Environment Scotland|publication-place=Edinburgh|access-date=2016-06-12}} A short distance to the west of the loch is Aultan Broubster a ruined stone circle. Several of the stones remain, five of which are upright with the largest being {{Height|m=1.3}} high.{{Cite web|url=https://canmore.org.uk/site/7705/aultan-broubster|title=Aultan Broubster|website=Canmore|publisher=Historic Environment Scotland|publication-place=Edinburgh|access-date=2016-06-12}}
The loch is a Scottish Natural Heritage Site of Special Scientific Interest for its Greenland white-fronted goose, Greylag goose and Whooper swans.{{Cite web|url=http://gateway.snh.gov.uk/sitelink/siteinfo.jsp?pa_code=1711|title=Loch Calder|website=Scottish Natural History information service|access-date=2016-06-12}}
The loch is popular for fishing and contains trout, Arctic char and ferox trout.{{Cite web|url=http://www.troutquest.com/caithness-g.asp|title=Caithness Lochs wild brown trout fishing|website=Troutquest|access-date=2016-06-12}}