Blue Earth River
Map of the catchment area
Blue Earth River at the Rapidan Dam in Blue Earth County ( 2007)
The Blue Earth River near the level of the USGS (2007)
Template: Infobox River / BILD_fehlt
Template: Infobox River / BILD_fehlt
Template: Infobox River / BILD_fehlt
The Blue Earth River is a 174 km long river in the south of the U.S. state of Minnesota.
Two of its source rivers flow a short distance to the north of Iowa. In Mankato it flows into the Minnesota River and is an indirect tributary of the Mississippi River. The river is the amount of water fro the largest tributary of the Minnesota River and contributes 46 % of the water of the Minnesota at the confluence of two waters at. The catchment area of Blue Earth Rivers covers 9029 km ² in an agricultural region. Nine-tenths of them are in Minnesota.
History
The river is named after the previous occurrence of a blue-green clay on its banks that are no longer visible bar today. The river's name in the language of the Dakota is Makato Osa Watapa, " the abundance of the blue earth is gathered ." The French explorer Pierre -Charles Le Sueur founded in 1700 near the estuary Fort L' Huillier. Purpose of the office was the reduction of Clay, either in the assumption that this copper contained or to ensure the financing of its fur trade activities by his superiors. The fort was abandoned a year later after an attack by the Fox Indians. During the 19th century the geographer Joseph Nicolas Nicollet found pits where the clay was won by the resident Indians. They used it for body painting. He found no traces of Le Sueur mines or from the Fort
Geography
The course of the Blue Earth River begins at the confluence of its western and central arm, about eight kilometers north of Elmore in the southwest of Faribault County. The Middle Branch Blue Earth River is 27 km long and is sometimes referred to as the main arm. It rises in the northwest of Winnebago County, about eleven kilometers east of rake. Its course aims westward into the Kossuth County and then northward into the Faribault County. The source of the 24- km-long West Branch Blue Earth River is located in Swea City in the north of Kossuth County. It runs in a north-easterly direction. These two sources are largely channeled. From the point of union of the Blue Earth River flows in a tortuous course through the east of Faribault County to the Blue Earth County. At Blue Earth opens the longest river source, the long East Branch Blue Earth River, which rises about 90 km in the south- Freeborn County and flows westward through the Faribault County.
The Blue Earth River still passes through the cities Winnebago and Vernon Center before it reaches Mankato, where he opens forth from the south to the Minnesota River. Rapidan Dam was built in 1910 for the purpose of hydroelectric development. He dammed the river about 19 km above its mouth. The reservoir was filled with sediment after its completion. The power was later discontinued, but resumed in 1984.
The two largest tributaries of the Blue Earth Rivers are the Le Sueur River, which flows five kilometers before the river mouth and the Watonwan River, whose mouth 26 km above the Minnesota River is located. These two rivers drain 31 % and 24% of the catchment area of the Blue Earth River. Among the tributaries at the headwaters of the Elm Creek heard in Winnebago in the northeast of Faribault County. Its 121 km long watercourse begins in northeast Jackson County. He always flows in an easterly direction to Martin County.
According to the Minnesota Pollution Control Agency, approximately 84 % of the watershed is used for agriculture, mainly the cultivation of corn and soybeans. The river is one of the most polluted rivers in Minnesota. Particularly high values reach sedimentation, bacteria, nitrates, phosphorus, mercury, polychlorinated biphenyls ( PCBs) and pesticides, which are mainly due to the washing away of the land surface of the watershed. Then there are the discharge of human waste from human settlements and livestock use. By no longer contemporary water purification plants and leaky septic tanks these contaminants reach a level that brings the state government to assess, the river is unsafe for swimming.
The Blue Earth River flows through mostly on a Grundmoränenebene, lying on the ground of a former glacial lake. The lower reaches of the north was once covered by a hardwood forest. This area was cleared for the most part for agricultural use. Below the Rapidan Dam, the river flows through a wooded ravine in the valley of the Minnesota River. This section is popular with canoeists.
Hydrology
The United States Geological Survey operates the Blue Earth River below the Rapidan Dam in Rapidan Township a level. It is situated between the mouths of the Watonwan River and the Le Sueur River, 19 km upstream of the mouth of the river into the Mississippi. The mean annual runoff of the river at this level averaged 1909-2005 30 m³ / s The highest recorded discharge rate during this period was 1220 m³ / s and was recorded on 9 April 1965, the lowest value was measured on 12 October 1955, 0.2 m³ / s.