The number of bacteria colonies can be influenced by weather and seasonal effects. This variability
makes the bacterial concentrations in natural water difficult to predict at any one time. Bacteria numbers
often increase following a heavy storm, snow melt or other excessive runoff. E. coli bacteria are often
more prevalent in turbid waters because they live in soil and can attach to sediment particles. Bacteria can
also remain in streambed sediments for long periods of time. If the streambed has been stirred up by
increased flow or rainfall, your sample could have elevated bacteria levels. This is why you should avoid
disturbing the streambed as you wade out into the stream. You should also collect the water sample
upstream from you. If you are collecting at several sites within the stream, collect the furthest
downstream sample first and proceed upstream.