Last week, Ranger Emily and our Land Stewardship team conducted a stream monitoring survey on Lenah Run, a tributary that flows through Willowsford into Broad Run, which eventually feeds into the Potomac River. Emily, who is certified as a stream monitor through Loudoun Wildlife, guided the team through the process of collecting, sorting, and identifying tiny aquatic creatures called benthic macroinvertebrates. These organisms, which live on the bottom of streams, are natural indicators of stream health.

By monitoring streams like Lenah Run, we gather important data to assess water quality and identify potential issues early. Understanding the condition of upstream waterways helps us protect the entire watershed, including Broad Run and the Potomac River.

What are Macroinvertebrates and Why do they Matter?

Macroinvertebrates are small creatures that live in the streambed. These creatures are highly sensitive to pollution, so their presence or absence tells us a lot about water quality. Some species are better able to tolerate pollution, while others cannot survive in polluted waters.

During the survey, the team found 224 organisms, including mayflies, beetles, clams, and worms. The diversity of species led to a stream health score of 8 on the Virginia Save Our Streams health index (on a 12-point scale), meaning the stream is neither in perfect condition nor critically impaired. This score gives us a reference point for future monitoring and helps us plan conservation efforts. 

What This Data Tells Us About Stream Health

The variety of species found in Lenah Run suggests that the stream is in the middle ground, but more monitoring is necessary to ensure long-term sustainability. While the stream’s health score shows that it isn’t in urgent need of attention, there is room for improvement. 

Since Lenah Run feeds into Broad Run, which faces water quality challenges, monitoring this smaller stream is an important step in preventing problems downstream. By keeping track of Lenah Run, we can identify potential issues early and address them before they affect the broader ecosystem. 

What Can Residents Do to Help? 

You don’t need to be a scientist to help protect our streams! Here are a few simple actions you can take: 

  • Limit Lawn Chemicals: Use fertilizers and pesticides sparingly, especially before it rains, to prevent them from washing into our streams.
  • Preserve Natural Buffers:  Keeping natural vegetation along stream banks helps prevent erosion and filters out pollutants before they reach the water. 
  • Avoid Dumping Waste:  Always dispose of waste, chemicals, and trash properly to avoid contaminating our streams. Remember, storm drains often lead directly to local waterways.
  • Get Involved: Anyone can become a certified stream monitor through Virginia Save Our Streams. It’s a great way to contribute valuable data, and you can even set up a monitoring site in your neighborhood.

Stream monitoring helps us understand the health of our waterways, and the macroinvertebrates we study provide important information about water quality. At Willowsford Conservancy, we’re dedicated to preserving our land and water. We encourage you to join us in these efforts, whether by participating in monitoring or taking simple actions at home to protect our streams. 

Have questions about stream monitoring or water quality? Feel free to reach out to our team!