Water Programs

Biological Stream Monitoring

Monitoring is an essential first step in the process of conserving and restoring our waterways. In addition to understanding the way stream systems work, monitoring can be used to assess the health of local waterways. Monitoring data can be used to document changes in stream or wetland health over time or to detect stress on the system.

Some government agencies and water resources biologists welcome the assistance of volunteer monitors. Many times government agencies lack the funding and staff to thoroughly monitor the nation's waters. In fact, only 19 percent of waterways in the United States are professionally monitored today (EPA 1996). Data collected by volunteers is used by government agencies to assess long-term trends in water quality. Volunteer monitors also help local governments by discovering acute pollution problems on streams, such as sewer leaks or chemical spills that require immediate attention.

Whether or not data is submitted to a government agency or university, water quality monitoring can help communities achieve stream restoration goals. Monitoring can help identify water bodies in need of restoration and prioritize water bodies for restoration. IWLA knows that monitoring on a regular basis is essential before, during and after stream restoration. Monitoring before a restoration project helps to assess the need for restoration and can reveal pollution problems that require immediate attention. Continued monitoring after restoration helps to document the benefits of the restoration and can alert your community to additional restoration. In addition, data that documents the positive effects of restoration on a waterway may help you obtain funds and government support for future restoration efforts.

There are many methods available to monitor the condition of waterways. Monitoring includes collecting data on the physical characteristics of the stream, water chemistry and the organisms living in the water.

A Watershed Approach

A watershed is all of the land from which rain, snow and underground springs drain into a stream or other water body. Land uses in the watershed affect the water quality of streams because any pollution on the land washes into the stream when it rains or snows. A background investigation of the stream along with a visual survey of stream and its watershed provide important information to identify potential sources of pollution, identify sites for additional monitoring, screen for pollution problems, and educate volunteers and the local community about potential pollution sources.

Save Our Streams Biological Stream Monitoring

The insects and crustaceans that live in a waterway are indicators of water quality because all organisms require specific conditions to live. The Izaak Walton League uses the presence of benthic macroinvertebrates to measure water quality. Macroinvertebrates are large enough to see with the naked eye (macro) and have no backbone (invertebrate). Benthic macroinvertebrates live in the benthos, or stream bottom, and include insect larvae, adult insects and crustaceans.

Stream-bottom macroinvertebrates are good indicators of water quality because they differ in their sensitivity to stress in the waterway. Some benthic macroinvertebrates are very sensitive to pollutants in the water. Others are less sensitive to pollution and can be found in almost any stream. Benthic macroinvertebrates usually live in the same area of a stream for most of their lives. Sampling these macroinvertebrates in a stream is a good indication of what the water quality has been for the past few months. If the water quality is generally poor, or if a polluting event occurred within the past several months, it will be reflected in the macroinvertebrate population.

SOS identifies three groups of macroinvertebrate taxa based on their sensitivity to pollution: pollution sensitive, somewhat pollution tolerant and pollution tolerant. The SOS method involves collecting a sample of macroinvertebrates from the stream, identifying the organisms and rating the water quality. Water quality ratings of excellent, good, fair and poor are based on the tolerance levels of the organisms found and the diversity of organisms in the sample. A stream with excellent water quality should support organisms from all three pollution tolerance groups.

Interested in biological stream monitoring? Visit our publications page or our need help page for more information.

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