Coon Branch Walk
8 February 2008: Walked upstream from the mouth of Coon Branch at the meeting point of I-495 and Little River Tpk to its last upstream outlets in Annandale.
The mouth of Coon Branch is a large culvert beneath I-495, joining Accotink Creek from the east inside the cloverleaf of the interchange. Across I-495, the stream flows through a small wooded area encircled by the cloverleaf ramp. Trash is evident here, but not as bad as the location might suggest. Serious erosion is also evident here, and along most of the rest of Coon Branch.
Above the cloverleaf, the stream flows through Annandale Park. The Invasive Management Area (IMA) plot managed by Joan Martinez is here, in a dense area of invasive alien multiflora rose and porcelainberry. Buffer is good here, but a sewer cut is mowed down to the bank in places.
Annandale Park, Hidden Oaks Nature Center, and the Packard Center form one contiguous area of park. The junction of Coon Branch and its eastern fork is in Annandale Park.
EASTERN FORK: The eastern fork flows along the south edge of the park. It is squeezed between the trails and baseball diamonds of the park and the houses along the south bank. The trail may be mowed excessively wide due to having a water main beneath it. Yards come right down to the bank and some are falling in. The southern bank is higher and steeper than the northern; it may have been built up during house construction. There is considerable riprap along the baseball diamond area.
Invasive alien species are prevalent in this area of the park. Invasives visible included garlic mustard, English ivy, privet, Japanese stilt grass, Japanese honeysuckle, wintercreeper, and pachysandra.
Above Hummer Road, the eastern fork flows briefly through several backyards. Buffer is limited or nil here. There is an apparently failed restoration here, with exposed fabric covering the streambed from bank to bank and riprap reinforcement.
Above that is the Manassas Gap Railroad Historic Park. Buffer is good in the park, but invasive alien species are rampant, including privet, garlic mustard, multiflora rose, mile-a-minute, and bush honeysuckle. Where the stream passes under the historic railroad bed, the downstream side is badly eroded and the upstream side disappears under mounded debris.
Above the main trail in the park (which seems to be a former road), trash is extraordinary. Beer drinking appears to be a frequent pastime here, and there is strong evidence that this park is the mythical "graveyard of the lost shopping carts".
Above the point in the park where the eastern fork again passes beneath the historic railroad bed, the park (and buffer) rapidly narrow to the limits of the railroad right-of-way, bordered on the south by apartments and on the north by single-family houses. There are water and sewer lines here, but they seem not to have been mowed for many years. The last upstream outlet of the eastern fork is at Medford Dr.
MAIN STEM: Above its junction with the eastern fork, the main stem of Coon Branch flows between Hidden Oaks Nature Center on the east and townhouses on the west. Buffer is broad on the park side, but varies on the other side from good to very narrow. Trails along the stream here are overused, with many areas worn down to bare soil along the banks, contributing to erosion.
A couple of spots in the townhouses along Butterfield Ln look like good candidates for revegetation or rain garden projects.
There is an impressive grove of mountain laurel on the east bank above Butterfield Ln.
On the hill above the stream, the nature center has a new parking lot, featuring permeable pavement and a rain garden. There is also a rain barrel and a sign explaining the features of the new parking area.
TRIBUTARY: At the north edge of the park, an intermittent tributary joins from the west. There is a dry stormwater pond along this tributary, with wooded banks and a stand of elderberry in the basin. But mile-a-minute is also prevalent in the pond. The tributary originates in an outlet at Trammel Rd, with a concrete channel below it.
Just above the dry tributary is the junction of two forks of Coon Branch. Although the western fork is clearly smaller, it is labeled the main stem on maps.
MIDDLE FORK: The other (middle) fork is outside the park here, flowing between single-family houses. Buffer varies. There is some mowing to the banks, some gabion rock walls, and much invasive English ivy.
Above Linda Ln, buffer is minimal or nil as the stream flows through front yards. Houses have bridges or culverts in their driveways. The middle fork flows parallel to Pleasant Ridge Rd here, often just a few feet from the road. There is much English ivy.
Above Marshal Dr, the source of the middle branch is inaccessible in backyards with little buffer.
MAIN STEM: From its junction with the middle fork, the main stem of Coon Branch is quite small, flowing between single-family houses. Backyards are mostly large, with fair buffer, but sometimes there is none. There is much erosion, but rather few attempts at reinforcement by property owners. Water flow gradually ends nearing Trammel Rd. Above Trammel Rd, there is no streambed, only roadside swales.
There are no storm drains in the neighborhoods north of Hidden Oaks Nature Center, allowing Coon Branch and tributaries to flow in daylight. Roadside drainage is grassy swales, but some of the steeper ones do show some erosion.
