C&O Canal, Riley’s Lock


Riley’s Lock, Lock 24, is at the mouth of the Great Seneca Creek, eight and one-half miles above Great Falls, Maryland.  In its heyday the area was a hub of commercial of activity.  The C&O Canal passed over the Great Seneca Creek via an aqueduct here.  Now, a foot bridge takes traveler’s across but the old stone works are still visible along with the original stone cutter’s initials carve into the stone.  The cutters were paid by the rock for each massive block.  Their initials represented a form of payment invoice.  To the southeast, the canal towpath is along beautiful stretches of the Potomac River shores.  Rapids demonstrate the power of the water.  To the northeast, the towpath is largely surrounded by trees but offers occasional views of river islands.  Due north from the lock, the Greenway Trail, mostly designed as a hiking trail, can be followed approximately 14 miles to the Visitor Center at Lake Clopper in Gaithersburg. 


Getting There


Take the Capital Beltway (I-495), to the River Road (Rte. 190) headed west, outside the beltway.  After 11.5 miles, turn left at a T-intersection to stay on River Rd.  At the bottom of the hill, in 0.7 miles, turn left onto Riley’s Lock Rd.  Park another 0.7 miles later just before the canal and river.  Riley=s Lock and the towpath are up the stairs directly ahead.


Area Routes


McKee-Beshers Wildlife Management Area (8.65 or 10.1 miles, VI or VIII)

The McKee-Beshers Wildlife Management Area (WMA) is mostly a flood plane of the Potomac River.  Within it are some farmed fields, aquatic ponds, and scattered deer.  It’s run by the state of Maryland and is hunted in during fall months.  The flat and mostly open land has some dirt roads through it which are good for running on.  The roads can however be muddy with large impassable puddles in wet seasons.  To get there from Riley’s Lock, follow the towpath northwest.  After an initial pond on the right, the canal northward is mostly a muddy ditch or completely dry.  The towpath can be very muddy after rains too.  Algonkian Park in Virginia is visible briefly, across the river on the left.  Three miles up, just after mile 26 of the towpath is the Horsepen Branch campground.  A sign, a small clearing, a water pump (this water should be treated before drinking from it) and portable outhouse are the only amenities to identify it.  At the pump, a dirt trail on the right side of the towpath crosses the dry canal bed into the WMA.  The trail leads to a double-track road.  Bear left on it going straight at other intersections.  The road becomes bigger and better defined before passing large ponds on the left and right.  After a gate at a T-intersection, turn right on the unmarked Hunting Quarter road.  This road is unpaved also but does get occasional auto traffic.  After crossing a creek, turn right at the first parking area and follow the dirt road back toward the river.  The dirt road becomes less and less defined as you near the woods but a dirt trail at the end of it does go through the woods to the towpath.  Turn left on the towpath and return to Riley’s Lock for the regular route. 


For an optional extension, turn left just before reaching Riley’s Lock, and after the pond on the left.  It leads to other dirt trails but take the unmarked gravel road up to River Road.  There watch for the fast moving traffic, then cross the Great Seneca Creek to Riley’s Lock Rd. immediately on the other side.  Jeb Stuart crossed the creek near this same location in 1863.  Finish on Riley’s Lock Rd. which leads back to the parking area. 




Blockhouse Point Conservation Park, Western Approach (9.55 or 11.1 miles; IX or X)

Getting to Blockhouse Point Conservation Park from Riley’s Lock is an excellent way to see the wilder side of the Potomac River up-close.   Using the towpath the canal is at first dry.  After Violet’s Lock, Lock 23, an intake from the river suddenly fills it.  Also at Violet’s Lock where Blockhouse Point begins, the river gets narrower and swifter.  Blockhouse Point is a rocky mound of earth that juts into and squeezes the river.   The water rolls and twists in rapids over the rocky bottom, with the entire river dropping 10 feet in one and a quarter miles.  At the point, the towpath becomes a narrow ribbon of land behind a concrete retaining wall, with the river on the right, and the canal and cliffs on the left.  You must pass Blockhouse Point Conservation Park in order to cross the canal at Pennyfield Lock (Lock 22), double-back and enter it from the east.  See Blockhouse Point Conservation Park, Southern Approach for a description of the regular route within the park.  The dirt trails on the optional extension are less used, more difficult to traverse and more difficult to navigate than those on the regular route.  They take you to the fenced western border of the park.   There, the stark difference between cattle grazed and badly eroded land contrasts sharply with beautiful tall trees, ferns and other undergrowth inside the park.  Though the trail getting to the western border is relatively flat, the return is over some short but steep up and down hills.  Return back to Riley’s Lock via the bridge at Lock 22 and the towpath. 


Nearby and Connecting Zones


C&O Canal, Great Falls, Maryland

C&O Canal, Edwards Ferry

Seneca State Park, Blacks Mill

Seneca State Park, Schaeffer Farm


What to do Afterward


Food and Drink



Entertainment and Edification

Seneca Schoolhouse Museum, circa 1868 - off River Road, west of Riley’s Lock Road

Edwards Ferry - old mill factory remains

Whites Ferry - an operational ferry over quiet waters of the Potomac takes people to Leesburg - 301 349-5200

McKee-Beshers Wildlife Management Area

Distance:          8.65 or 10.1 miles

Rating:              VI or VIII ; flat dirt roads and towpath


8.65 Mile Route


R     0.0   from the bridge over Riley’s Lock (Lock 24)

       0.05 trail X on R crosses canal shortly after crossing the Great Seneca Creek

       0.2   mile mark 23; pond on R

       1.15 mile mark 24

       2.15 mile mark 25; Algonkian Park across river

       2.8   trail X on R (unmarked) into McKee-Beshers WMA


R     3.15 trail X on R at Horsepen Branch camp; trail is near water pump; camp is after mile 26


BL  3.5   onto double-track dirt road (unmarked); go straight at all intersections

R     4.05 Hunting Quarter Rd at T after gate (unmarked gravel road)

       4.55 creek crossing

R     4.9   dirt road at parking area (unmarked)

       5.25 Rd X


L     5.85 C&O Towpath between towpath miles 25 & 26 (same as mile 2.8)

       6.5   mile mark 25; Algonkian Park across river

       7.45 mile mark 24

       8.45 mile mark 23; pond on L


       8.55 trail X on L crosses canal ditch after pond on L

       8.65 Riley’s Lock (Lock 24)




*10.1 Mile Route


L     8.55 trail X on L crosses canal ditch after pond on L


R     8.7   Tschiffely Mill Rd (unmarked, gravel); mill remains on L


R     9.35 River Rd crosses Great Seneca Cr (!)


R     9.4   Riley=s Lock Rd (Greenway Trailhead to Clopper Lake is L 0.05 miles)


     10.1   parking for Riley’s Lock


Blockhouse Park, Western Approach

Distance: 9.55 or 11.1 miles

Rating:           IX or X; flat shaded towpath and some hills on unpaved trails in Blockhouse Park


9.55 Mile Route


L     0.0   from the bridge over Riley’s Lock

       0.65 Violet’s Lock (Lock 23)

       2.0   petroleum pipeline


L     3.15 Pennyfield Lock (Lock 22); follow the path past parking and onto Pennyfield Lock Rd


S     3.45 into parking as Pennyfield Lock Rd turns R up hill


L/R 3.5   to canal & over Muddy Br Creek

       3.6   trail turns R and leaves canal


S     3.65 at pumping station clearing go S to gravel road w/creek on R (note the concrete block here to find the location of the trail on return)


L     3.85 trail X on L; begin the hill

       4.25 trail bears L at wood fence

       4.55 trail X on L merges


L     4.65 gravel road in pipeline clearing; downhill; parking on R for alt Start

       4.9   trail X on R


L     5.15 double track road at T before canal


R     5.9   2nd trail on R to return to canal (near pumping station and concrete block)


L/R 6.05 leave canal  for the road at parking

       6.1   Pennyfield Lock Rd joins from L


       6.3   gate at end of parking


R     6.4   onto towpath at Lock 22, Pennyfield Lock

       7.6   petroleum pipeline

       8.9   Violet’s Lock (Lock 23)

       9.55 Riley’s (Lock 24)



*11.1 Mile Route


S     4.65 gravel road X in pipeline clearing


L     5.1   trail X on L (gate blocks horses) at western border of park

       5.25 trail X on L


BL  5.55 trail X on R crosses stream; start steep uphill ahead

R     6.0   trail X at T; steep downhill ahead


R     6.45 gravel road at T in pipeline clearing (pickup cues at mile 5.15 on 9.55 mile route)