Siltation

Siltation is water pollution caused by particulate terrestrial clastic material, with a particle size dominated by silt or clay.

Although "siltation" is not perfectly stringent, since it also includes particle sizes other than silt, it is preferred for its lack of ambiguity.

The result will be an increased amount of silt and clay in the water bodies that drain the area.

[1] Another important cause of siltation is the septage and other sewage sludges that are discharged from households or business establishments with no septic tanks or wastewater treatment facilities to bodies of water.

While nekton have been found to avoid spill plumes in the water (e.g. the environmental monitoring project during the building of the Øresund Bridge), filtering benthic organisms have no way of escape.

Unlike in the sea, in a stream, the plume will cover the entire channel, except possibly for backwaters, and so fish will also be directly affected in most cases.

The sediment transport in open water is estimated by measuring the turbidity, correlating turbidity to sediment concentration (using a regression developed from water samples that are filtered, dried, and weighed), multiplying the concentration with the discharge as above, and integrating over the entire plume.

Parameters to measure are sediment accumulation, turbidity at the level of the filtering biota, and optionally incident light.

In rural areas, the first line of defense is to maintain land cover and prevent soil erosion in the first place.

In urban areas, the defenses are to keep land uncovered for as short a time as possible during construction and to use silt screens to prevent the sediment from getting released in water bodies.