Located in Timber Branch Park, along the banks of Timber Branch, one of the tributaries to the Cameron Run watershed. This small stream was once a site of Native American settlement, but it has been channeled and developed by the urbanization process and is now mostly underground.
It now "originates" a few dozen meters north of the intersection of Braddock Road and Valley Drive, emanating from a culvert and a boggy area with several small seeps and springs. From there it flows through Timber Branch Park, Ivy Hill Cemetery, and into the Rosemont neighborhood, where it disappears into a culvert at West Alexandria Street.
I've managed to find a topo map from 1885 and another from 1943 which clearly show the stream's origin at a spring located close to the intersection of what are now Kenwood Avenue and Crestwood Drive. I've identified the likely spot as a small collection of rocks behind the Agudas Achim synagogue at N38° 49.893', W077° 04.880' (see photo). A line of lush vegetation and some man-made features (storm drains, manhole covers, etc.) show the old watercourse path out to the intersection of Crestwood and Valley Drive. From here it meanders under Valley Drive to the present outlet culvert.
At the other end, in 1943 the stream flowed above ground past the present culvert at West Alexandria St., turned east between West Glendale St. and West Spring St., then turned south to parallel the east side of Commonwealth Avenue, passed under King Street, then down Diagonal Road to the present outlet, now known as Hooff's Run, which flows into Cameron Run by the Alexandria National Cemetery.
This is a very popular area for joggers and walkers. It is bounded by East & West Timber Branch Parkway, which is where most of the foot traffic will be. There is a small trail along the west side of the stream bed that you can access from the footbridge, and the cache is located very close to the trail. You'll be relatively concealed when the foliage is in season, but in the winter you'll need to exercise some discretion when you look for it.
When you're done, take a stroll through Ivy Hill Cemetery. You'll pass the grave of Wernher Von Braun (WMQY7 on waymarking.com) before the road banks left down the hill and over the stream to the cemetery's other entrance.
Congrats to The First Noel with the FTF...
