Over the summer, I took part in a stream monitoring activity with the Northern Virginia Soil and Water Conservation District as an additional activity to my Independent Research Project. Specifically, I went to the Ellanor C. Lawrence Park in Fairfax, VA to monitor the Big Rocky Run stream. This park is located in the Chesapeake Bay watershed and is drained primarily by five different streams, including the Big Rocky Run stream. Big Rocky Run is considered a moderately impaired stream, meaning that it fails to meet a few water quality standards. In the past, Big Rocky Run has experienced bank erosion, silt deposition, and changes in the channel size. Currently, there have been efforts to implement Riparian restoration projects to protect the stream’s ecological health.
Though there are various ways to measure stream health, I followed the method involving aquatic macroinvertebrates. Aquatic macroinvertebrates are organisms that are found in freshwater ecosystems. They are small primary consumers that feed on live organic material, detrivores that break down leaves and debris, and also predators to other macroinvertebrates. There are found in all aquatic ecosystems, making them effective indicators for environmental health. As aquarian and riparian habitats are becoming more vulnerable to pollution, land development, and other harmful human-related activities, aquatic macroinvertebrates are often monitored to detect potentially-dangerous changes in an ecosystem.
Steps to Stream Monitoring
I first located a part of the stream where the water was moving relatively fast, and, several inches above the direction of the water’s movement, I used a small rake to disturb the sediment there. By simultaneously placing my net facing opposite to the direction the water was moving, I was able to collect benthic macroinvertebrates in my net due to the soil disturbance. Then, using a pair of tweezers and a small brush, I examined the organisms I found. To identify them, I made use of the Creek Critters mobile app, which provides step by step instructions on how to identify benthic macroinvertebrates. Several benthic macroinvertebrates I found include caddisflies, mayflies, stoneflies, water pennies, leeches, and damselflies.
These benthic macroinvertebrates are indicators of stream quality. For example, a stream containing benthic macroinvertebrates that are tolerant of impairment would indicate poor water quality. Considering that most of the benthic macroinvertebrates I collected, such as the caddisfly, mayfly, stonefly, water penny, and damselfly were fairly sensitive to pollution, the Big Rocky Run stream had a fairly good water quality. Although I did find one leech, overall, the quality of the water in Big Rocky Run was fair.
Importance of Stream Monitoring
Fairfax County includes over 800 miles of streams, many of them draining into the Chesapeake Bay Watershed. Many essential human activities are dependent on healthy watersheds. Given this, keeping Fairfax County’s watersheds healthy ensures that the water we use and the ecosystem we live in is protected. Today, there is a growing amount of chemicals being exposed to our ecosystems, endangering the purity of our clean water ecosystems. Monitoring corrosive water can prevent toxic chemicals from impacting the water we use. Such events have occurred in Washington D.C and Flint, Michigan. However, regardless of the situation, ecosystems of hundreds of organisms will be affected. Thus, stream monitoring provides us the knowledge needed to effectively manage and protect our vulnerable ecosystems.