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3. Stream habitats: CQHEI

Apr 4th, 2014 by

This video from the USGS (US Geological Survey) introduces some of the physical habitat features that you will observe while at the stream.

The CQHEI is a survey that examines a series of characteristics of a stream channel itself and the surrounding area, known as a riparian zone. The purpose of the survey is to give researchers or environmental managers a quick and easy way of evaluating stream condition.

The basic assumption behind the survey is that examining the basic physical condition of the stream can provide you with an estimate of the biotic condition of the stream. “Biotic condition” meaning the number and different types of organisms that can be supported by the stream environment.

The CQHEI survey considers several factors:

  • Substrate: This examines that type of material that makes up the bed of the stream. A stream bottom made of large rocks creates small cavities which provide habitat for stream invertebrates, while smaller rocks provide less habitat. Silts or sediments present in stream water from erosion can fill in these spaces and remove habitat even where the rock size is good.
  • Fish cover: Streams like Juday Creek are important spawning areas for large game fish like trout, and smaller fish that live in the stream throughout their life cycle. Tree roots, boulders, and downed trees provide pool (slow moving water) habitats for fish. These same structures are also important because they serve as “retention devices” – structures that trap organic matter (leaves, etc.) and keep it in a local area of a stream where it can be used as a food source.
  • Stream shape: Over time, a natural stream will develop several bends or “meanders” as water erodes that stream banks. In areas impacted by human activity, streams are often “channelized” or forced into a straight and restricted path.
  • Riparian area: In our area of the country, a complete riparian zone would be a wooded areas with trees and shrubs. The riparian plants provide an important source of nutrients for stream organisms, as leaves and other organic matter falls into the stream. A well developed riparian zone also helps stabilize the soil to prevent runoff of silt into the stream, and may serve as a buffer to absorb contaminants washed into the area.
  • Depth and velocity:  A stream with deep pools will provide habitat for larger fish. A fast moving stream will stay better aerated and supplied with oxygen.
  • Riffles:  A natural stream has an alternating pattern of riffles (small rapids) and pools. Riffles are important for aeration of the water, and often provide important habitat for invertebrates.

A CQHEI score greater than 60 is generally considered sufficient to support a biotic community. Streams scoring over 100 would be considered excellent condition.    Here is an example of a completed CQHEI:

Sample CQHEI

Concept Check Questions:  (Answer on Sakai)

Which of the following stream conditions would be considered “healthy” on a CQHEI? (select all that apply)

1.  Stream substrate composed large rocks without sediment filling in the spaces between rocks.

2.  A stream composed entirely of pools, without small rapids.

3.  A stream with meanders and curves.

4. A stream that containers large boulders and downed trees.

5.  A stream with a riparian zone that is composed of manicured grass.

Why do you think a physical survey like CQHEI can be used to estimate the status of living organisms in a stream?

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