Agriculture significantly alters the natural condition of all freshwater systems. Examining specific impacts of certain chemicals on separate taxa or sub-societies in river systems was the previous reductionist notion of pollution, which was basically an Eco toxicological concept. It is currently less effective than a extra rounded method that considers the scheme as a whole and incorporates physical effects such as river channel drainage and physical alteration, catchment modification, and nutrient, particle, and biocide contamination. The European Water Framework Directive acknowledges this indirectly by mandating the restoration of water bodies to a condition of "excellent ecological quality," which is defined as "just slightly different from pristine." The consequences for agricultural organization are much more serious than most people realize.