Size: A large cove that opens onto the north side of the main reservoir.

Habitat: This cove is bordered on three sides by deciduous and coniferous woods. In late summer and early fall, extensive mudflats may exist. The water level varies from season to season and from year to year.

Best Months: March through May; late July into early December (or until freeze-up). The attractiveness of this location is heavily dependent on the water level which determines if or when mudflats emerge or whether there is sufficient water for migrant waterfowl.

Coverage Time: Thirty minutes to an hour or more.

Trails/Paths: South of a wooden gate adjacent to the parking lot, a level beaten path runs parallel to the east side of the cove along the base of a slope. The west side of the cove is not open to the public.

Notable Birds: Snow Goose, Gadwall, Northern Shoveler, Redhead, Red-breasted Merganser, Wild Turkey, Least Bittern, Red Knot, Sanderling, White-rumped Sandpiper, Baird’s Sandpiper, Dunlin, Stilt Sandpiper, Short-billed Dowitcher, Lesser Black-backed Gull, Common Raven, Olive-sided Flycatcher, Gray-cheeked Thrush, Prothonotary Warbler, Connecticut Warbler, Brewster’s Warbler, Lawrence’s Warbler.

Amenities: Paved parking lot with a boat ramp. A portable toilet is present during the boating/fishing season.

Handicapped Access: The paved parking lot provides distant sightlines to the water/mudflats. The path south of the wooden gate is level for some distance;
portions are rocky.

Operation and Hours: Triadelphia Reservoir and the surrounding land is owned and operated by the Washington Suburban Sanitary Commission (WSSC) dawn to dusk spring, summer, and fall except during fall deer hunts. Everyone needs a pass, which can be obtained at the cabin at Brighton Dam. WSSC has granted access to additional adjacent land not available to the general public. See Additional Land Open for MOS Members. The reservoir is closed to public access during the winter.

The gravel entrance road is gated just before the parking lot. When the gate is closed, do not park and enter as you may be cited for trespassing. Security after 9/11 means an orange or higher alert closes public access to the reservoir.

Special Attractions: Pigtail is one of the county’s few consistent shorebird  locations (mostly mid to late summer); it can also be good for waterfowl (early spring and mid-fall) and passerines (spring and fall).

Nearby Sites: Big Branch, Brighton Dam.

Compiler: Joanne Solem

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