Citizens Help Gauge the Health of Alexandria’s Streams

Volunteers sort through a stream sample for macroinvertebrates. Photo by Jennifer Fletcher, City of Alexandria Communications.

By Devin Reese

Urban streams get dirty—from trash, discharges, and street runoff. Yet, they have the potential to be the lifeblood of communities, offering a place for fishing, boating, picnicking, biking, birdwatching, and various activities that attract people to the water’s edge. ARMN and other organizations conduct volunteer stream cleanups to remove larger trash. Also, the City of Alexandria  takes care of its waterways through a network of green infrastructure (Best Management Practices) and other stormwater management strategies to filter pollutants before they reach waterways. Now, the city is taking steps to grow a participatory program to monitor the health of its streams.

The program is a biological stream monitoring initiative that invites citizen participation, starting with two events this fall. Last Saturday, I participated in the first one—sampling macroinvertebrates in Taylor Run Stream. These are the “benthic” macroinvertebrates (stream bottom animals without spines that are big enough to see with the naked eye), which include insects, insect larvae, worms, snails, crustaceans such as crayfish, and mollusks such as freshwater clams. Whereas the city’s chemical testing provides a measure of stream quality at the time of sampling, macroinvertebrates monitoring provides a window into quality over time because of their sensitivity to contaminants.

For example, organisms such as stonefly larvae and gilled snails are indicators of good water quality because they are sensitive to pollution. Organisms such as damselfly larvae and net-spinner caddisfly larvae are somewhat sensitive, serving as indicators of fair water quality. And organisms like leeches and black fly larvae are so pollution-tolerant that they can live in poor-quality water.

Looking to macroinvertebrates as indicators of stream “health” was originally conceived during the 1980s, in response to the 1977 Clean Water Act, to supplement traditional chemical monitoring with biological data. Now, Virginia, through its Department of Environmental Quality (DEQ), uses a specific protocol called Virginia Save Our Streams (VA SOS), which was developed by the conservation organization Izaak Walton League to standardize macroinvertebrate sampling across Virginia waterways.

Under the leadership of Anthony Minnick, Alexandria’s Water Quality Compliance Specialist, we used the VA SOS protocol to collect data in the Angel Park area of the Taylor Run Stream near the Masonic Temple. The protocol calls for sampling until you’ve collected at least 200 macroinvertebrates or sampled from a maximum of four kick seine nets. First, we deployed a net in a stream riffle—an area where the water was moving quickly over rocks. By anchoring the bottom of the net, we reduced the chance of organisms slipping underneath. After 60-90 seconds, volunteers carefully extracted the net and carried it horizontally, collection side up, to avoid losing organisms.

Then the meticulous work began. We sorted through the debris collected by the net, watching for movements of small organisms. We found caddisfly larvae, aquatic worms, and the occasional leech or snail. With the help of magnifying lenses and keen eyes, we recovered even miniscule insect larvae no bigger than fingernail clippings. Using delicate paintbrush tips, sticks, and plastic tweezers, we removed each organism from the net into an ice cube tray filled with stream water. Most of the organisms would not have survived for long without water immersion.

While some volunteers continued picking through the net, others started the painstaking process of detailing the organisms. Peering into each ice cube tray section, we tallied the number of each type of organism, using benthic macroinvertebrate ID keys. The exercise generated conversation and collaboration to identify the smaller and more challenging organisms. For example, participants debated whether the caddisflies we were finding were the more pollution-tolerant “net-spinning” caddisflies (family Hydropsychidae) or the “finger-net” caddisflies (family Philopotamidae) that indicate better water quality. The net-spinners can be distinguished by a row of three armored plates behind their heads, plus more feathery tails.

Once we all understood the protocol, the group settled into an assembly-line-like efficiency, with volunteers returning to the stream to collect an additional three samples, picking through the sampling net to pluck out organisms, identifying them, and tallying up counts of each type. When we found something unusual that indicated higher water quality, like a water snipe fly larvae, there were exclamations of excitement. Organisms that were not part of the macroinvertebrate count, like a couple of northern two-lined salamanders (Eurycea bislineata), also created a stir of enthusiasm.

Said ARMN volunteer-in-training Jaya Chavern, “I think through both the process of stream monitoring and the identification, because . . . I’m not going to learn it deeply unless I do it myself with my hands; I’m learning it much more meaningfully than watching training videos.”

By the third seine net, we had almost reached the target of 200 organisms, and the fourth sample did the job. We completed the sampling just ahead of the three hours planned for the event, but the fall monitoring work was not complete. Anthony ran a second event at Holmes Run Creek in Alexandria the following weekend. He plans to run at least two fall and two spring macroinvertebrate monitoring events annually, with the goal of gradually expanding the sites beyond Taylor Run and Holmes Run.

After the events, Anthony tallied the results into the percentages indicated by the DEQ protocol. He explained to me how he would submit those onto an ArcGIS (web-based mapping) site, which classifies health of the stream based on those tabulations. And then organizations such as EPA and DEQ can access the data. Explained Anthony, “this is part of a larger process in which, anywhere in the Chesapeake Bay, they’re able to pull that information about a waterway and look at its health.”

Our data from the Taylor Run event is already in the Clean Water Hub, which collates VA SOS data from the entire region from this sort of biological monitoring as well as other volunteering water monitoring events coordinated by the Izaac Walton League. The data we collect in these volunteer events adds to the big picture of stream health in Virginia and beyond.

These events also bring people together in rewarding ways. Said Kayla Hinrichs, who became an ARMN-certified master naturalist in 2024, “The things that keep bringing me back to stream monitoring: It’s outside, near the water (these are things humans like), and there’s always just really interesting, nice people. And there’s this excitement of discovery, like you really don’t know what you’re going to find. So, curiosity, bucolic environment, and nice people!”

Anthony noted that, in addition to spring and fall macroinvertebrate monitoring events, the city plans to conduct spring, summer, and fall stream cleanups, as well as periodic storm drain marking events. The environmental stewardship event calendar is typically updated one to two months in advance of major activities and can be found here: https://www.alexandriava.gov/TES. Individuals and organizations interested in future opportunities or in developing their own environmental stewardship initiatives in Alexandria may contact Anthony for information or assistance at: Anthony.minnick@alexandriava.gov.

You can also watch for opportunities to get involved in biological stream monitoring in Fairfax County or Arlington County when they plan their next rounds of spring 2026 events. If you get really interested in biological monitoring, DEQ also offers a stepwise process to nominate waterbodies for monitoring and/or start your own water monitoring. You can also get certified to Become a Monitor by the VA Save our Streams initiative.