The Stream Reach

The typical stream reach has riffles, pools and runs and should be perennial. The X-site (X) is the furthest downstream location, it is usually where the latitude and longitude readings are taken. The reach is measured from this point upstream. Water samples and flow should be collected as close to the (X) as possible if suitable features are available. In high-gradient streams your benthic samples are collected from riffles/runs. Always move in an upstream directions so that your water and benthic samples are representative. For certain habitat conditions a right and left side is determined; this is done by looking downstream.
Most agencies that survey rivers and streams use 100-meters as the reach length. Volunteers are encouraged to use the same length but other lengths are also acceptable. Streams may meander and have thick vegetation so the entire length of the reach may not be visible. Under these circumstances the length of the reach can be reduced as a safety precaution, especially if younger volunteers are monitoring. If you reduce the size then your reach should have at least one riffle, run and pool if possible.
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