Benthic Macroinvertebrate Surveys

Loudoun Wildlife has been conducting benthic macroinvertebrate surveys around the county since 1996. We submit our survey data to Virginia Save Our Streams (VA SOS), a program administered by the Izaak Walton League of America (IWLA). VA SOS then approves and aggregates the data for the state and submits it to the Virginia Department of Environmental Quality, which in turn uses the information to identify impaired streams to target for further monitoring, habitat restoration and pollution control efforts.

Loudoun Wildlife is a partner with IWLA’s Clean Water Hub, where all our biological and chemical data are accessible by individual sites. If you are interested in viewing this data, click on “Explore the Map” and type in “Loudoun Wildlife Conservancy” in the search by organization field.

You can learn more about our sites and view data from our active survey sites by clicking on the site names beneath the map near the bottom of the page.

Stream Monitoring Teams

What We Monitor: Our stream monitoring program involves sampling benthic macroinvertebrates, which are the insects and other small creatures that live at the bottom of streams. The type and quantity of aquatic organisms tell a good story about the quality of water in the stream.

When: Stream monitoring is conducted twice a year, in the spring and the fall.

How: A certified monitor conducts a survey of a stream’s health with a team of volunteers using the Virginia Save Our Streams (SOS) monitoring protocol. The equipment such as nets, magnifying glasses, and field tables, are provided by Loudoun Wildlife Conservancy.

Team members wade into the stream and use a net to collect a sample of aquatic organisms.The organisms are then sorted, identified, and recorded on a data sheet before they are released back into the stream. Once the sampling is completed, the raw data is plugged into a series of formulas to compute a score of stream health ranging from one (unacceptable ecological condition) to twelve (acceptable).

Time Commitment: It takes a monitoring team approximately three hours to complete a survey and generate a score of stream health. Volunteers assist by transporting equipment, holding the net in the stream, placing sample aquatic organisms in collection trays, and counting the number of each type of organism collected. Volunteers are not required to have experience in stream monitoring and will be given instructions by the certified stream monitor who leads the survey.

Learn More: View our video series and sign up for our monthly email newsletter, The Monitor, or view it online.

To join a team, contact Amy Ulland at aulland@loudounwildlife.org.

Where We Monitor

We currently have 24 active sites (JK Black Oak Wildlife Sanctuary has two) all over the county. Click on a site name beneath the map to learn more about, and see the data for, that site.