Nutrients are important to support biological activities in the water. Depending on the water body type, the natural amount of nutrients varies.
The Our and Sauer are lower mountain streams that are supposed to have a low nutrient and high oxygen content. Therefore, these streams harbour specific species such as the brown trout and river mussel that prefer low nutrient contents. Concentrations above the natural level cause high occurrences of death rates in juvenile organisms.
However, more and more nutrients are carried into the waters through a variety of factors:
- Run-off from agricultural land (fertilizers, manure)
- Run-off from purification plants
- Erosion of field tracks caused by rainwater
- Fertilization in close proximity to the water
- Erosion from cattle, excreta