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.
- Description: Stream reach diagram with additional information.
- Description: A perennial stream or perennial river is a stream or river (channel) which has
constant stream throughout the year through parts of its stream bed during years of normal rainfall.
- Description: This section describes procedures and considerations for collecting water
samples from wadeable stream reaches. For more information visit the programs overview of chemical
integrity, or for more specific considerations regarding the design of a water quality monitoring program
refer to the program’s Volunteer Manual.
- Description: The stream’s velocity (flow) is modified by conditions along and around the
- Description: BMIs are animals without a backbone that can be seen with the naked eye, and
have to the ability to cling to bottom surfaces such as rocks, leaves or roots. They include crustaceans,
mollusks and annelids but in many aquatic environments most of the macroinvertebrate community are the
larvae of aquatic insects.
- Description: The habitat evaluation process involves rating many different habitat
conditions as optimal, suboptimal, marginal or poor based upon criteria (descriptions and a rating scale)
included on the survey data sheets.