On the Stream
Be sure to dress for being outside. Wear long sleeve pants and shirts, wear sneakers or sturdy shoes with socks, and dress for the weather. We will provide all the equipment needed for the stream survey, including waterproof boots.
You will take measurements of temperature, velocity (how fast the water flows), and other physical characteristics of the stream and its surroundings.
We collect and identify insects and crustaceans that live on the stream bottom, called benthic macroinvertebrates. The macroinvertebrates that live in a waterway are an indicator of water quality because all organisms require specific conditions to live. They 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.
Macroinvertebrates are good indicators of water quality because they differ in their sensitivity to water pollution. Some benthic macroinvertebrates are very sensitive to pollution and cannot survive in degraded water. Others are less sensitive to degradation.
Benthic macroinvertebrates usually live in the same area of a stream for most of their lives. Monitoring these organisms provides a good sense of what the water quality has been for the past few months. If the water quality is generally poor, or if a pollution event occurred within the past several months, it will be reflected in the macroinvertebrate population.
For monitoring streams, we divide macroinvertebrates into three groups based on their sensitivity to pollution: Pollution sensitive, less sensitive, and tolerant. First, we collect the macroinvertebrates. You will be up to your elbows in the stream turning over rocks and kicking around in the streambed dislodging whatever might be hidden there to be caught with a net downstream. Then we bring the net to the shore and pick all the bugs off the net, separate them, and identify them. Water quality ratings of excellent, good, fair, and poor are based on the pollution tolerance levels of the bugs found and the diversity of bugs in the sample.
When a pollution problem is detected by a lack of aquatic organisms, a chemical analysis of the water may help to pinpoint the cause of problem. Chemical monitoring involves taking a sample of the water and analyzing its chemistry to discover the presence of abnormalities. Project Watershed staff will collect information on temperature, pH, dissolved oxygen, biological oxygen demand, turbidity, total dissolved solids, nitrates, phosphates, and fecal coliform bacteria using very accurate automatic probes. Depending on how long your class is able to spend at the stream, you may also be able to run tests on stream water for some of these chemical parameters. Either way, you will learn about water chemistry and what they readings for your stream mean about water quality, pollution, and your stream’s health.