Seneca Creek State Park, Black Rock Mill

Seneca Creek State Park, Black Rock Mill

Situated in the middle of Seneca State Park and the middle of the Greenway Trail, Black Rock Mill is a good place to start exploring. Unlike the northern end of the park and the trail, there are hardly any developed amenities for many miles in either direction of Black Rock Mill. Lake Clopper is over 5 miles north. The Visitor Center there is 6.2 miles distant. The C&O Canal, in the other direction, is 7.2 miles south. Other than bridges, and a few road crossings, there’s not much else made by man in-between. Running or hiking the trail definitely gives you a feeling of being out in the country. Neither suburban developments nor rural housing are yet visible from most of the sections of the trail described here. Few people frequent the area mostly because the Greenway trail is new but also because of the long out-and-back distances. Don’t let that stop you. Just turn around at a distance comfortable for you and you’ll have a nice run.

The namesake mill is located right off Black Rock Rd. west of Darnestown. The site is one of Montgomery County’s nicer outdoor exhibits. Inside the walls of the now roofless old building, displays tell the history and some of the mill’s gearing machinery is preserved hanging, giving a sort of cut-away view of a milling operation. A steady supply of water used to be supplied by a dam that was located 200 ft. upsteam. The dam no longer exists and the startling high water marks on the inside of the walls show the magnitude of the floods that came over the last century.

Rolling tree covered hills surround the banks of the Great Seneca Creek from the mill, northeast and southward. As of 2005, The Greenway Trail goes from Damascus Recreation Park to the C&O Canal and will one day bridge the Potomac and Patuxent rivers. An additional access to areas south of Black Rock Mill can be gained by parking near the bridge at Darnestown Rd., Rte. 28. The trail northeast of here is described in the route description below.

Going south from Black Rock Mill on the Greenway Trail it is 1.1 miles to Rte. 28 and is a little hilly. After ups and downs in the woods, it crosses along the edge of a farm field where large herds of deer can be seen. Beyond Rte. 28, the next four-and-a half miles are fairly flat, mostly shaded and very runnable until reaching Berryville Rd. Between Berryville Rd. and the Seneca Rd., the next 1.4 miles begins with a tributary creek crossing and an initial steep hill that is followed by successively easier ones. A final flat straight stretch of 0.75 miles on the road leads to the C&O Canal and Potomac River at Riley’s Lock and the mouth of the Great Seneca Creek.

An area close to the Black Rock Mill is the Schaeffer Farm section of Seneca State Park. It is just north of the mill and a favorite of mountainbike cyclists. The White Trail there can be reached by going up a steep hill on Black Rock Rd. and turning left only a half mile distant. See Seneca State Park, Schaeffer Farm for routes there.

Getting There

From the Capital Beltway (I-495), take I-270 headed west. Stay in the right lanes. About 5 miles from the beltway, take Exit 6, Darnestown Rd., Rte. 28 headed west. Follow the signs bearing right at the light onto Key West Ave. to stay on Rte. 28 where Darnestown Rd. bears left. Rte. 28 road has been rerouted. Key West Ave. later joins and becomes Darnestown Rd. again. Turn right 9.6 miles from the beltway on the easy to miss Black Rock Rd. It’s only 0.3 miles past Berrville Rd. on the left. The mill parking is 0.6 miles from Rte. 28 near the bottom of the hill on the left side of the road.

Area Routes

To Riffleford Rd. and Back (9.25 miles, X)

If you want to see a lot of the Great Seneca Creek, this route offers the longest stretches in which it is visible from the Greenway Trail. The dirt single-track is broken up by a few road crossings allowing for measurable, early turnaround points. The full trip uses the loop portion of the Long Draught Trail (see Seneca State Park, Lake Clopper). Hikers will immediately recognize the first portion near Black Rock Mill to be more like places found in the Shenandoah National Park. The heavy forest growth keeps it cooler in hot weather, and there are some rocky areas in the creek and on the hills. Many good fishing holes are passed early. Two major hills are hit early on also. The first is long but the second is not. After crossing Rte. 118, the trail becomes easier as it flattens through some fields and aligns itself again with the creek. Some areas of tall grass may pose an obstacle however. I encountered grasses on the sides of the trail 6 and 7 ft. tall in two places. Ahead I ran into a ranger and a volunteer who coincidentally were mowing it, coming from the other direction (call Friends of Seneca Creek State Park at 301 924-2127 if you wish to contribute or participate; volunteers were key to creating this local gem). Ticks in summer are a problem so if you find the same tall grasses, be sure to check yourself thoroughly to avoid Lyme disease. On a warm day, I pulled off more ticks on a round trip than I have fingers to count on. Another thing that may unsettle some is the sound of gunfire. Local gun clubs target practice on the opposite banks of the creek. The sound can be heard for miles. There are deer on that side that didn’t look too happy about it. The trail is beautiful however and well worth exploring. Several wooden bridges make getting across gullies and side streams easy. A few old trees with trunks of 6 ft. in diameter can be seen. Great Blue Heron and other birds fish or bath in the waters. Several portions of the trail are on top of old dykes. The turn around on the Long Draught Trail’s loop, actually past Riffleford Rd., includes the only other hill of the course. Cycling is only allowed on the Long Draught Trail portion of this route.