by Matthew Chasse

Make your own D-net. The net is named for the "D" shape of its frame. It is used to collect stream insects from the bottom of a stream. You can make one at home (but make sure an adult is around to help!).

Materials you will need
42" x 14" piece of screen 42" x 2" piece of canvas or heavy cloth Thread and needle  Scissors Wire coat hanger Wire
Drill with 1/8" and 1/4" bits Wooden broom handle
Pliers Duct tape
Directions for building a D-net
Building a D-net

1. Fold the screen in half (21" x 14") and cut screen (as shown).
2. Sew the two pieces of screen together along the cut edge.
3. Fold the canvas in half along the open edge of the net.
4. Untwist the wire hanger and cut off the top (as shown).
5. Bend the smaller cut piece into a U-shape.
6. Drill a 1/4" hole in the flat end of the broom stick.
7. Drill two shallow 1/8" holes on the sides of the broomstick, positioned so you can fit U-shaped wire over the flat end and into the holes.
8. Slip large wire into the folded canvas slot of the net and twist the ends together.
9. Cut the twisted wire to no longer than 2" in length and insert into hole at flat end of the broomstick.
10. Secure the net to the pole using the U-shaped wire and duct tape (as shown).

Volunteer Water Quality Monitoring

Non-profit Stream Monitoring Organizations

County Stream Monitoring Groups

Maryland DNR's Teaching Environmental Awareness in Maryland (TEAM) program offers students a two-part stream investigation in a local freshwater stream of their choice. At this streamside setting, trained volunteers guide them as they learn about water quality, stream habitats and the community of organisms that inhabit the stream. Using the information they collect, the students will then formulate conclusions about the health of the stream they have investigated. If you are interested in becoming a TEAM volunteer and helping educate Marylanders about our natural resources, visit our website at and fill out an application.

It's a known fact kids are drawn to streams and waterways. Some visit them to fish, hike, canoe and kayak or just enjoy nature; others want to learn more about them and how people affect their overall health. Streams offer students a unique outdoor field experience and a window to understanding their local environment and the Chesapeake Bay.

Why Streams?
Maryland's 8,800 miles of streams form the life support system for the Chesapeake Bay watershed by providing important habitats for many aquatic and terrestrial organisms. Each stream plays a vital role in linking the Chesapeake Bay to its surrounding watershed.

Many kids think of a stream in terms of the trout they caught while fishing or the crayfish they found while exploring its banks. These are some of the more visible examples but they are only a fraction of the diversity contained within Maryland's streams. Upon closer examination you can find fish, amphibians and insects that are invisible to the casual observer. More important, many of these organisms are biological indicators of stream health, especially the insects or macroinvertebrates.

An Outdoor Classroom Realized
Each year thousands of students experience Maryland's streams through programs offered by the Department of Natural Resources (DNR) outdoor education centers, and summer camps. However, students, parents or teachers can organize their own stream investigations. Using a stream as an outdoor classroom offers kids an incomparable hands-on learning experience that leads them to a greater understanding and appreciation of their natural environment.

Getting to Know Macroinvertebrates
Prior to going out and doing an actual field investigation, students should learn how to identify some of the basic types of stream insects and stream habitats Sorting and identifying macroinvertebrates.they might encounter, either through classroom exercises or home study. Stream insects are one of the most important indicators of the long-term health of a stream. Many are long-lived and spend most of their lives within the stream. Some, like stoneflies, are highly sensitive to pollution while others such as blackfly larvae are very tolerant. During a field investigation, many of these insects may be seen; however without some initial preparation, students will not have the proper knowledge and skills to conduct a meaningful investigation of a stream.

In the Field
After completing the classroom or home study of stream insects and their habitats, it's time to consider a field investigation. The best time to conduct one is typically in spring or late fall when weather conditions are most favorable for being outside. First and foremost, the stream must be accessible to the students. Those on the school grounds are ideal but streams on other public lands are also an option.

Sampling woody debris with a D-netPrior to going out to the stream, students will also need to have some sampling equipment. A net, preferably a D-net, is used to sample for macroinvertebrates. However you can also just use your hands and look under rocks to get a sample. It's also helpful to have a bucket to put your sample in, a magnifier, tweezers and a tray with a white background. The white background provides good contrast for seeing the darker macroinvertebrates.

Once at the stream, look for riffles or woody debris to sample. A stream riffle is a shallow area where rocks break up the flow of water. This area is highly enriched in oxygen and has lots of small spaces for macroinvertebrates to hide in. Woody debris found in the water -- leaves, sticks and tree roots -- is another important habitat as these materials provide an important food source for stream insects.

In addition to looking at the macroinvertebrate community within the stream, you may also decide to sample for dissolved oxygen levels, pH, depth, water flow and turbidity. All provide important information on the physical and biological conditions of the stream. You should end the investigation by making some basic conclusions about the health of the stream.

By using streams as outdoor classrooms, students are making an important and meaningful connection to the Chesapeake Bay watershed; they learn monitoring techniques and problem- solving skills that will benefit them for a lifetime.

Expanding Our Investigation
Maryland DNR currently offers opportunities for middle school students to conduct a stream investigation. Those interested in learning more about DNR's student streams investigations should visit or contact Matthew Chasse at 410-260-8828, or

Check out our website for more information at

Matthew Chasse
is an Education Specialist for DNR's Conservation Education Division, the TEAM Program Coordinator, and serves on the Education Matrix Team.

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