A term usually used in reference to Idaho Code Title 42, Chapter 38, the Stream Protection Act.  An alteration is any human-directed activity that obstructs, diminishes, destroys, alters, modifies, relocates, or changes the natural existing shape of the stream channel within or below the mean high water mark.  It includes removal of material from the stream channel and emplacement of material or structures in or across the stream channel where the material or structure has the potential to affect flow in the channel as determined by the director of the Idaho Department of Water Resources.  Generally, any activity using mechanized equipment that moves or overturns gravel or earth in a stream.