Triadelphia Reservoir


  • Open April 1 - November 30 only.
  • Triadelphia Reservoir and Rocky Gorge Reservoir are owned and operated by the Washington Suburban Sanitary Commission (WSSC). Triadelphia is oriented slightly northwest to southeast along the Patuxent River which serves as the boundary between Howard County to the east and Montgomery County to the west. The two reservoirs are surrounded by 4,000+ mostly wooded acres.
  • Triadelphia is the larger of the two reservoirs and attracts a wide variety of birds not consistently seen elsewhere in the county. Access to this reservoir, although limited, is much better for birders than that at Rocky Gorge.
  • Although boating and fishing are allowed, shore access is minimal. Birders may view portions of this reservoir at three public sites in Howard County: Brighton Dam, Big Branch, and Pigtail. There are separate site guides for each. In addition, from Montgomery County, views from the parking area at Greenbridge Road and the trail down to the reservoir at Triadelphia Lake Road allow birders to look across the water into Howard County territory. These two locations are shown on the accompanying map with directions only. Consult A Birder's Guide to Montgomery County, Maryland (2nd. ed.) for complete information on these two.
  • Notable birds: Cackling Goose, Eurasean Wigeon, Surf Scoter, White-winged Scoter, Black Scoter, Long-tailed Duck, Wild Turkey, Northern Bobwhite, Red-throated Loon, Red-necked Grebe, Western Grebe, Least Bittern, Snowy Egret, Little Blue Heron, Tri-colored Heron, Cattle Egret, Glossy Ibis, Bald Eable, Rough-legged Hawk, Golden Eagle, Peregrine Falcon, Sandhill Crane, Black-bellied Plover, American Golden-Plover, American Avocet, Ruddy Turnstone, Red Knot, Sanderling, Western Sandpiper, White-rumpted Sandpiper, Baird's Sandpiper, Dunlin, Stilt Sandpiper, Short-billed Dowitcher, Long-billed Dowitcher, Wilson's Phalarope, Sabine's Gull, Iceland Gull, Lesser Black-backed Gull, Glaucous Gull, Black Tern, Common Tern, Forster's Tern, Olive-sided Flycatcher, Alder Flycatcher, Philadelphia Vireo, Common Raven, Marsh Wren, Gray-cheeked Thrush, Snow Bunting, Golden-winged Warbler, Prothonotary Warbler, Connecticutt Warbler.
Triadelphia Lake Road (directions) Big Branch Pigtail Greenbridge Road (directions) Brighton Dam Triadelphia Reservoir
  • Reservoirs are open from April 1 to November 15. While day use or seasonal permits are required for boating and fishing (along with state fishing licenses), birders do not need a pass. They are, however, subject to the same restrictions as shore fishermen. Rangers are security personnel. They enforce regulations and issue citations for trespassing as well as for fishing and boating violations.
  • Bird and dragonfly species lists for all Triadelphia and Rocky Gorge reservoir Howard County sites have been combined.
  • Each reservoir site has a photo page. In addition, there is a page titled Triadelphia Reservoir Bird Photos.
  • Hunting is allowed in defined areas; a free map is available at the Brighton Dam office. Dates are posted at each public access site at the beginning of the hunting season. The entire reservoir is closed on hunting dates.
  • For additional reservoir information, visit the WSSC website at and click on Public Information or call the Brighton Dam Information Center 301-774-9124.
Triadelphia Reservoir Compiler: Joanne Solem

© 2009