ABSTRACT
Station locations can be chosen without regard to other means of access if the stream is navigable by an available boat. Sampling stations should not be established at locations where mixing is incomplete, or where significant differences in water composition exist in the stream cross section. Chemical characteristics of the water have an impact on the aquatic organisms in a stream, and biological reactions in turn affect chemical characteristics. One approach for determining sampling frequency is to consider whether the stations are basic or auxiliary stations. Accordingly, the frequency of sampling at auxiliary stations may be considerably higher than for basic sampling stations. Artificial physical structures such as dams, weirs, and wing walls can cause changes in hydraulic flow patterns and thus influence the representativeness of the water quality at specific locations. Basic stations are used for classifying water resources, collection of baseline data, and determination of water quality.
