Rottnan

{{Infobox river

|name = {{native name|sv|Rottnan}}
{{native name|no|Rotna}}

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|image = Rotna.jpg

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|image_caption = River Rotna in Svullrya, Norway

|map = {{Infobox mapframe|wikidata=yes|zoom=6|marker=water|stroke-color=#0000FF|coord={{coord|60.1905|12.6656}}}}

|map_caption = Interactive map of the lake

|subdivision_type1 = Countries

|subdivision_name1 = Norway, Sweden

|subdivision_type2 = Counties

|subdivision_name2 = Innlandet, Värmland

|subdivision_type3 = Municipalities

|subdivision_name3 = Åsnes, Grue, Torsby, Sunne

| length = {{convert|110|km|mi|abbr=on}}{{Cite encyclopedia |title=Rottnan |encyclopedia=Nationalencyklopedin |url=http://www.ne.se/rottnan |language=Swedish |accessdate=2010-07-14}} {{Subscription required}}

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| discharge1_avg = {{convert|12.9|m3/s|cuft/s|abbr=on}}{{Cite web |title=SMHI |url=http://www.smhi.se/polopoly_fs/1.3780!Qstat_20090604.xls}}

| discharge1_max = {{convert|63|m3/s|cuft/s|abbr=on}}

|source1 = Lake Helveteskjelda

|source1_location = Åsnes, Norway

|source1_coordinates = {{coord|60.55034|12.4229|region:NO}}

|source1_elevation = {{convert|520|m}}

|mouth = Lake Mellan-Fryken

|mouth_location = Rottneros, Sweden

|mouth_coordinates = {{coord|59.793310|13.129954|display=inline,title}}

|mouth_elevation = {{convert|62|m}}

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|basin_size = {{convert|960|km2|sqmi|abbr=on}}

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{{native name|sv|Rottnan}} or {{native name|no|Rotna}}{{Cite web |title=Informasjon om stadnamn |url=https://stadnamn.kartverket.no/fakta/309132 |access-date=2025-06-14|website=Norgeskart |publisher=Kartverket |language=no}} is a {{convert|110|km|adj=on}} long river in Norway and Sweden. The river starts south of the Hof Finnskog Church in Solør, Norway and discharges into lake Mellan-Fryken at Rottneros in Värmland, Sweden. The main river begins at the Rundtjern, but that lake is fed by several streams and small lakes on and surrounding the Evensbergklinten and Husuberget mountains. The highest source is the small lake Helveteskjelda, at an elevation of {{convert|520|m}} above sea level. The river passes through the municipalities of Åsnes and Grue in Innlandet county, Norway and through the municipalities of Torsby and Sunne in Värmland County, Sweden.{{Cite SNL|Rotna|Rotna|2025-06-14|Thorsnæs|Geir|2024-11-25}}

Rottnan used to have three waterfalls close to the mouth in Fryken. Rottnafallet was the last and tallest at {{convert|26|m}} height. The waterfalls were built in 1927 for hydroelectric power. The name Rottnan comes from the old Swedish word Rotn which means "the roaring".

File:Skarpedsfallet.jpg|The waterfall Skarpedsfallet in Rottneros, Sweden

File:Rottnafallet.jpg|The waterfall Rottnafallet and the pulp mill Rottneros bruk in Rottneros, Sweden