Part of the recently-designated Occoquan Water Trail, historic Bull Run is a little jewel of a stream hidden away in bustling Northern Virginia. Bordered by wooded parkland to the east and mostly undeveloped tracts to the west, you hardly know you are in the midst of two of the most populous counties in the state. Its waters originate from a spring at the edge of the Piedmont, and are fed along the way by Youngs Branch which traverses Manassas Battlefield, Cub Run (a suburban whitewater run) and other little tributaries. Bull Run ends at the peaceful but lengthy flatwater of the Occoquan River/Reservoir.
Two sections of Bull Run are navigable by kayak or canoe: the 3+ miles above Rt. 28 running through Bull Run Regional Park, and the 8.5 miles from Rt. 28 to Yates Ford Rd. alongside Hemlock Overlook Park.
The upper section is shallow and meandering and the current can be swift, making for a fun paddle. The bridge at Rt. 28 is the site of the Battle of Blackburn's Ford, be careful with the ledge here. Below Rt. 28 there are several Class I riffles and shoals that keep the trip interesting, and one Class II just past the railroad bridge that requires turning sharply left then right through a decent wave. A little further downstream you can take a nice lunch break at the island where Pope's Head Creek trickles in from the left. Beyond that, you'll come to the remnants of an old dam where the power lines cross overhead; another slight ledge and maneuvering around the rocks here.
As the stream winds through the Hemlock Overlook area you may hear gunfire echoing through the woods from the nearby Fairfax Rod & Gun Club -- evoking mental images of the great Civil War battles that took place nearby. Unfortunately the current runs out as you hit the deadwater above the Occoquan Reservoir, and there's an hour yet of flatwater paddling to get down to Yates Ford Rd. Fortunately the woods and hillsides are scenic, you can say hi to the hikers along the way and there's a variety of wildlife to be seen -- ducks, geese, hawks, turtles, the occasional blue heron. We even spotted what appeared to be bright orange & white carp playfully swimming just off our bow.
No public facilities downstream of Bull Run Regional Park. Plenty of woods on river left if you get the urge... river right is all private property and shooting ranges.
Bull Run Regional Park charges a $7 per car entrance fee in season (they don't call it "Faretax" county for nothing!) Parking at the Rt. 28 bridge and the upper lot near Bull Run Marina is free. If you visit the Stone Bridge and Manassas Battlefield, there is a $3 per adult fee.
From Manassas go north on Rt. 28 (Centreville Rd.) until you come to the Bull Run bridge and Prince William/Fairfax county line. Turn left after the bridge into the gravel parking lot.
Bull Run Regional Park - 38 47' 56" N, 77 29' 37" W
Stone Bridge - 38 49' 28" N, 77 30' 13" W
Rt. 28 Bridge - 38 48' 11" N, 77 26' 58" W
Yates Ford Rd. Bridge - 38 44' 32" N, 77 23' 11" W
The upper section is easily accessed from the gravel banks behind the first picnic shelter just past the entrance to Bull Run Regional Park, or after a good rain you might be able to put in further upstream, at the Manassas Battlefield Stone Bridge on Rt. 29, which has its own parking lot.
There's a parking lot at Rt. 28 on the upstream side, access point for the water and hiking trails. (Get there early on weekends because it fills up with hikers.) The put-in here is a little tricky, as the banks are eroded and there's a rocky ledge just before the bridge. You can put in just to the left of the bottom of the steps leading down from the parking lot, below the ledge and above the riprap. Or if you want to run the ledge, put in on the opposite bank.
The take-out at Yates Ford Rd. is the site of Bull Run Marina, for which you would have to purchase a gate key. Instead, go past the marina docks and under the bridge, and take out at river left. There is a paved path leading up the bank to the large parking lot where the county dumps free mulch. It's only about a 100 yard carry. You can leave a car here and shuttle back to Rt. 28.
Check the ST45 water gauge at http://www.owml.vt.edu/owmlgis/index.asp (login with userid & password "guest"). A level of around 3 ft or better is runnable.