Søo

{{short description|River in Trøndelag, Norway}}

{{distinguish|Soo (disambiguation){{!}}Soo}}

{{Infobox river

|name = Søo

|name_native =

|name_native_lang =

|name_other =

|etymology =

|image = Søo i Hemne 01 2012.jpg

|image_size =

|image_caption = The Søo seen from the dam at the west end of Lake Vasslivatnet

|image_alt =

|map = {{Infobox mapframe|wikidata=yes|zoom=9|marker=natural}}

|map_caption = Interactive map of the river

|subdivision_type1 = Country

|subdivision_name1 = Norway

|subdivision_type2 = County

|subdivision_name2 = Trøndelag

|subdivision_type3 = Municipality

|subdivision_name3 = Heim Municipality

|length = {{convert|30|km|mi|abbr=on}}

|width_min =

|width_avg =

|width_max =

|depth_min =

|depth_avg =

|depth_max =

|discharge1_location =

|discharge1_min =

|discharge1_avg =

|discharge1_max =

|source1 = Lake Søvatnet

|source1_location = Heim, Orkland, Rindal border

|source1_coordinates = {{coord|63|13|24|N|09|18|32|E|region:NO}}

|source1_elevation = {{convert|270|m}}

|mouth = Hemnfjorden

|mouth_location = Kyrksæterøra, Heim Municipality

|mouth_coordinates = {{coord|63|17|38|N|09|05|19|E|display=inline,title}}

|mouth_elevation = {{convert|0|m}}

|progression =

|river_system =

|basin_size = {{convert|237.93|km2|sqmi|abbr=on}}

|basin_landmarks =

|basin_population =

|tributaries_left =

|tributaries_right =

|waterbodies =

|waterfalls =

|bridges =

|ports =

}}

The Søo{{Cite web |title=Informasjon om stadnamn |url=https://stadnamn.kartverket.no/fakta/680817 |access-date=2025-01-18|website=Norgeskart |publisher=Kartverket |language=no}} is a river in Heim Municipality in Trøndelag county, Norway. The {{convert|30|km|sp=us|adj=on}} long river originates at Lake Søo (Søvatnet), which lies on the border of Orkland Municipality, Heim Municipality, and Rindal Municipality. The lake sits at an elevation of {{convert|280|m|sp=us}}. It then flows into Lake Vassli (Vasslivatnet), which sits at roughly the same elevation, depending on levels behind the dam. The inflow to the Søo is regulated by a dam {{convert|20|m|ft|sp=us|}} high at the west end of Lake Vassli, which serves as a regulation reservoir for the Søa Hydroelectric Power Station.{{Store norske leksikon|Søa_kraftverk|Søa kraftverk|2025-01-18|Rosvold|Knut A.|2024-11-25}}

Its course flows from Lake Vassli through the Søo Valley (Søvassdalen) parallel to European route E39 highway. Further down towards the village of Vinjeøra, it turns northward about {{convert|2|km|sp=us}} east of the village. Norwegian County Road 680 follows the river northwards as flows into Lake Ro (Rovatnet; {{convert|13|m|ft|sp=us|disp=or}}). As the water exits the lake, it proceeds about {{convert|2|km|sp=us}} to the east through the village of Kyrksæterøra before it empties into in the Hemnfjorden.