Where are the Samples Collected?
Samples are collected from as close as possible to the middle of the stream – the midpoint of the depth and midpoint of the width – to ensure the sample is representative of the stream as a whole. In addition, samples are collected near a stream gauging station so that the volume of the stream at the time of sampling is known. Knowing the stream volume is important for computing the amount of nutrients in the stream and interpreting water quality. When are samples collected? Samples are collected twice per week during runoff periods, such as spring snowmelt and storm events, because overland runoff is the main pathway through which contaminants are transported from land to stream. As stream flow subsides, samples are collected less frequently (once per week to once every other week to once per month). How are samples collected? Clean plastic bottles are rinsed three times with stream water, and then fully immersed into the stream, upstream of any local disturbances (such as animals or
