10-year monitoring program once construction is complete includes:
- Streambed surveys
- Structure surveys
- Vegetation surveys
- Biological Surveys
Must meet success criteria outlined in Mitigation Banking Instrument or it will be fixed.
The Glade stream restored.
Red Shouldered Hawk in the Glade.
Volunteer Stream Monitoring Program
Reston Association has been monitoring streams within Reston for over 10 years using the Virginia Save Our Streams protocol. Many sites are within the restored stream sections in Snakeden Branch and The Glade.
Reston Association is also partnering with United States Geologic Survey (USGS) and the South Lakes High School to track the recovery of Snakeden Branch with students from the International Baccalaureate program. Since 2010, students have been collecting habitat, flow, chemistry and benthic macroinvertebrate data. The data is then processed to determine the state of the stream recovery.
Iron Bacteria in The Glade
We have noticed an orange, rust colored precipitate coating the bottom of The Glade stream valley recently. It is due to iron bacteria which is prevalent in this area. The bacteria feed off the iron rich soil and the by-product is an orange precipitate that coats the bottom of the stream. After a rain storm, it washes away, but will return when there is sufficient iron for the bacteria to feed on. We have seen this in all parts of Reston, as well as conferred with Fairfax County ecologists who confirmed it is all over the county where they do monitoring.
The material used to reconnect the stream to the flood plain is comprised of a mixture of sand, silt, topsoil, leaf mulch and a variety of sized rocks. There were no contaminated materials used in this process during the stream restoration project.
It can be hypothesized that before restoration, the water was at a lower elevation and the groundwater may have been flowing through layers of soil that were low in iron. After restoration, the groundwater begins to rise back up to a new higher elevation and is flowing through layers of soil that is rich in iron.
As the streams re-establish the aquatic life, bugs, etc, the bottom of the stream will look a little different from when they first placed the materials in the stream. Leaves drop and decompose, algae and diatoms will coat rocks, and organisms leave their marks as well.
While stream monitoring in The Glade, we have been able to catch a couple of fish and salamanders along with macroinvertebrates including cranefly larvae and netspinning caddisflies. Since spring we have also seen wood frogs and a number of other frogs and toads hatch from The Glade.
Larval Mosquito Surveillance
During a 3-year period, RA contracted Clarke to perform larval mosquito surveillance in Reston at restored and unrestored stream sites.
The report states there does not seem to be a significant difference in larval mosquito populations between restored and unrestored sections of stream in Reston, VA.
Natural predators of mosquitoes were observed with much higher frequency in restored streams than unrestored streams due to the presence of a more balanced ecosystem.