Stream surveys

Have you ever seen photos of schoolchildren or adults wading in streams or rivers and wondered just what they were doing? Chances are these people were assisting with Maryland’s Biological Stream Survey.

Stream waders at work on Sideling Hill Creek

Credit: Maryland DNR

The Biological Stream Survey Program began in 1993 to monitor the condition of the nearly 12,600 miles of streams and rivers that are found in Maryland. The purpose of this program is to assess the current condition of our waterways, identify problem areas, provide an inventory of the plants and animals that inhabit these areas, gauge the success of restoration and conservation efforts, build a long term database, and communicate the results of this survey.

From this data, waterways are assigned a grade on how healthy they are. There are a number of professional biologists and “Stream Wader” volunteers that help conduct portions of these surveys. During the spring, the inventory is concerned mostly with small aquatic animals, also known as macro invertebrates, and the collecting of water samples.

During the summer months, surveys look at fish populations, stream chemistry, other wildlife populations and the physical condition of the stream. Evaluating these parameters provides a snapshot of the health of the stream and the surrounding ecosystem.

One way of evaluating the relative health of streams is to sample the numbers and kinds of aquatic macro invertebrates that occur in a section of the stream. Biologists use these small insects, worms and shellfish as samples because they are common and easy to collect, they have a fairly long lifespan, and they usually stay within a small section of the stream.

Knowing that certain species are very sensitive to pollution while others can tolerate poor water quality provides a glimpse of the purity of the water. Indicators of good water quality include mayflies, stoneflies, caddisflies, riffle beetles and gill breathing snails. Intermediate water quality includes freshwater clams, mussels, crayfish, dragonflies, and damselflies. Animals that can tolerate poor conditions include leeches, midges, black flies, worms and lung-breathing snails.

Therefore, a preponderance of stoneflies, mayflies and riffle beetles in a stream indicates good water quality.

Water samples are also evaluated for their dissolved oxygen, pH, acid neutralizing capacity, and amount of nitrogen and phosphorus present, each being an indicator of water quality. In most cases, the more dissolved oxygen found, the better the water quality.

The presence of high concentrations of nutrients such as nitrogen and phosphorus can promote dense plant growth such as “algae blooms,” which impacts the health of the stream. The influence of acid rain is causing some streams to develop a lowered “acidic” pH which can be harmful to aquatic plants and animals. Thus, the pH and buffering capacity of the stream is another important health consideration.

In addition, evaluating fish and wildlife populations provides a clue of the relative health of the stream. Observing species like brook trout in a stream is a very good indicator of stream health, since this fish is very sensitive to water quality or temperature changes.

Finally, looking at the color or condition of the water and the stream banks provides a glimpse into stream health. A healthy stream has clear, cool water and wide stream banks that have not eroded.

Frederick County contains some very high quality “first order” streams, along with some waterways with rather poor water quality.

You can learn more about this subject online by going to the Maryland Biological Stream Survey

Article by FCFCDB

Nature Notes for 11/29/2015