At a Glance

Hours: Daylight hours year-round.

Cost: Free.

Tips: Spotting scope recommended. ◾ Restrooms are at the parking areas. ◾ Picnic tables are located at Riley’s and Violette’s Locks. ◾ For more amenities, see

Best Seasons: Year round.

Breeding Bird Atlas Blocks: Seneca CW, Seneca CE

Local MOS Chapter: Montgomery Bird Club

C&O Canal – Pennyfield, Violette’s & Riley’s Locks

Pennyfield – 12100 Pennyfield Lock Road, Potomac, MD 20854
Violette’s – 13001 Violettes Lock Road, Germantown, MD 20874
Riley’s – 13001 Rileys Lock Road, Germantown, MD 20837
(301) 495-4500

The stretch of the C&O Canal in Montgomery County that contains Pennyfield Lock, Violette’s Lock, and Riley’s Lock offers a rich diversity of habitat, including the Potomac River, flooded portions of the C&O canal, and adjacent woodlands, impoundments, and marshes that provide varied birding opportunities for migrating, nesting and over-wintering birds. Violette’s Lock itself is the #1 eBird hotspot in Montgomery County, with over 270 species reported, and Riley’s Lock and Pennyfield Lock are not far behind.

This 3.2-mile stretch of the C&O Canal is but a small portion of the 184.5-mile C&O Canal National Historical Park, operated by the National Park Service. The canal parallels the Maryland shore of the Potomac from Allegany County in western Maryland all the way to Washington, DC. For reference, it helps to know that the locks along the canal, used in earlier times to control water levels for navigation, are numbered starting at the downstream end at Washington, DC., and go up to Lock 75 near Cumberland in Allegany County. Locations along the canal are also denoted by mileposts, which again are numbered starting at Washington, DC.

Pennyfield Lock is Lock 22, located at Milepost 19.6; Violette’s Lock is Lock 23, at Milepost 22.1; and Riley’s Lock is Lock 24, at Milepost 22.8. Part of the Riley’s Lock area is occupied by the 20.2 -acre Seneca Landing Special Park, operated by Montgomery County Parks. The National Park Service map at the trail link map at left provides a good overview, and another good reference is the detailed “Chesapeake & Ohio Canal 2018 Park Planner” which lists facilities by milepost  in a plain text version. The same information is presented in a fancier format with graphics and icons in the “Recreational Guide and Park Planner.”

Some of the best views of the Potomac River are provided at Violette’s Lock and Riley’s Lock.  Note that the river and canal run approximately east-west along this stretch. An early morning birder might want to proceed west from Pennyfield toward Violette’s and Riley’s in order to keep the sun at your back. The approximately 3.2 mile walk from Pennyfield to Rileys could be birded in a half-day. The approximately 6.4 mile round trip would constitute a full day of birding. An alternative would be to bird with a friend and use two cars, parking one at each end.


Over 265 species have been reported on eBird from this section of the C&O Canal. There are separate eBird hotspots for the three canal locks:

Of note in this area of the canal are the abundant warblers during spring migration, and many nesting species including Bald Eagle, Prothonatory Warbler, occasional Cerulean Warbler, Louisiana Waterthrush, Baltimore Oriole, and owls, flycatchers, swallows, herons and woodpeckers. Migrants of note include Bonaparte’s Gull and Forster’s Tern. Over-wintering waterbirds include ducks, grebes, and coots. A good assortment of shorebirds turns up during migrations. The Pennyfield-Violette’s-Riley’s area is known for sometimes hosting Sooty Terns or a Pomarine Jaeger in the aftermath of a hurricane.

Pet Policy:

Pets must be on a leash no longer than 6 feet and must be under physical control at all times.

Wheelchair Access: 

Some sections of the C&O Canal Towpath are wheelchair accessible, but the path is graded gravel and conditions are subject to change depending on weather. For more about accessibility, see At Seneca Landing Special Park on Riley’s Lock Road, there is a fully accessible floating boat launch for kayakers and canoeists and an accessible picnic area with tables and grills.

Special Designations:

The C&O Canal and bordering lands within Montgomery County are part of the Lower C&O Canal Important Bird Area, as designated by the National Audubon Society.

Special Features:

At Seneca Landing Special Park on Riley’s Lock Road includes a boat ramp for motorized boats, a fully accessible floating boat launch for kayakers and canoeists, and an accessible picnic area with tables and grills. ◾ Nearby, the historic Seneca Store (formerly know as Poole’s Store), is located at 16315 Old River Road, Poolesville. ◾  Many other spots along the canal offer boat launch and other facilities. See the brochure at for a handy summary of features at each site. Or see for more details. ◾ The C&O Canal is rich in history. Explore the many historical features of the C&O Canal National Historical Park. ◾ The Canal Trust has produced a mobile app, the C&O Canal Explorer, with over 600 points of interest mapped  in a searchable format, allowing you to find hiking trails, campgrounds, history, trailheads, parking, and more at a glance, along the entire length of the Canal.  The app is available to download for 99 cents and runs on Android and IOS devices. ◾  Wake up with the birds along the Canal: through the Canal Quarters Program, visitors may arrange for overnight stays at seven historic lockhouses along the Canal: five in Montgomery County, one in Frederick County, and one in Washington County. See for details.

There’s a new trail in town: the Great Allegheny Passage is a 135-mile hiker-biker trail that follows an old railway right of way from Cumberland, MD, to Pittsburgh, PA, essentially forming an extension of the C&O Canal Towpath. Construction of the Great Allegheny Passage was completed over a 35-year period and the last section was opened in 2013. The 20.5-mile section in Maryland, from Cumberland to the Pennsylvania State line, is often called the Allegheny Highlands Trail. The surface of the Passage is hard-packed crushed stone and can accommodate wheelchairs.

The local chapter of the Maryland Ornithological Society is the Montgomery Bird Club, which offers field trips and meetings with informative programs, all free and open to the public.◾ The Montgomery Bird Club has published A Birder’s Guide to Montgomery County, Maryland; this comprehensive, detailed printed book covers 17 major birding sites plus 18 “little treasures” in the county. To order, see


Packed dirt, gravel and potholes at Riley’s Lock; graded gravel and sand at Violette’s and Pennyfield. The parking area at Seneca Landing Special Park is gravel.


These directions will take you sequentially from Pennyfield to Violette’s to Riley’s Locks.

To reach Pennyfield Lock from I-495/DC Beltway: Take Exit 39 for MD Route 190/River Road. Proceed west on River Road for approximately 8.5 miles and then turn left (south) onto Pennyfield Lock Road; the preceding intersection is Travilah Road. Follow Pennyfield Lock Road for about 0.7 miles to its dead-end near the C&O Canal. Park in the lot.

To reach Violettes Lock from Pennyfield Lock: Return to River Road and turn left (west) and drive approximately 2.6 miles to Violette’s Lock Road. Turn left (south) and proceed about 0.6 miles to the parking area at the end of the road.

To reach Riley’s Lock/Seneca from Violette’s Lock: Return to River Road and turn left, which will take you northwest. At the T-intersection with Seneca Road, turn left to remain on River Road. Then turn left (south) onto Riley’s Lock Road at the bottom of a long hill. It is just under 1 mile along River Road from Violette’s Lock Road to Riley’s Lock Road. Proceed about 0.7 miles to the parking area at the end of the Riley’s Lock Road. Note that Riley’s Lock Road floods easily and may have standing water.

Nearby Sites:

Montgomery County: Black Hill Regional Park, Blue Mash Nature Trail, Little Bennett Regional Park, Lois Y. Green Conservation Park, McKee-Beshers Wildlife Management Area (Hughes Hollow), Rock Creek Regional Park – Lake Needwood, Rock Creek Regional Park – Meadowside Nature Center & Lake Frank, Seneca Creek State Park, Wheaton Regional Park – Brookside Gardens, Brookside Nature Center, Pine Lake Area


Bottomland DeciduousHedgerows Forested SwampFreshwater Marsh or FloodplainMud Flats (Tidal or Non-Tidal)Rivers & Streams


BeginnersBicycle Trails (Bikes may be prohibited on some trails)Boat or Canoe/Kayak LaunchFishingFree - No Entry Fee at Any TimeHiking/Walking TrailsHistorical FeaturesParkingPets AllowedPicnic AreaRestroomsWater ViewWheelchair Accessible FeaturesYoung People / Families


#1 Hotspot in County or CityAudubon Important Bird AreasC&O Canal AccessHiker-Biker Trails (Paved)National Parks & MonumentsThe Rivers of the Western ShoreWater Trails