Conowingo Dam Site Guide
by Rick Blom

NOTICE: Rick Blom passed away on December 11, 2002.

(The Conowingo Dam Annotated Checklist is also available.)

Conowingo Dam is located in northeastern Maryland on the Susquehanna River just northwest of where the river empties into the northern part of the Chesapeake Bay. It is about eight miles above the town of Havre de Grace. If you are looking at a road map, Havre de Grace is where Interstate 95 crosses the Susquehanna. The precise location of the dam is where Route 1 crosses the river. Route 1 crosses the river on top of the dam. Access to the base of the dam, and to gull and other birdwatching, is from Route 1. Just south of the river, turn east on Shuresville Road. After one-half mile, make the first left, onto Shures Landing Road. Follow the road to the parking lot at the base of the dam, where it dead ends. Most observation is done from the area closest to the dam at the far end of the parking lot. There is a pavilion there which provides shelter during bad weather. The parking lot is open every day of the year from at least 6:00 a.m. until 10:00 p.m. Shuresville Landing Road is steep and winding and may not be passable immediately after snowstorms but it is quickly cleared because it is the access road for workers at the dam. There are public bathrooms at the pavilion. Just north of the dam, on Route 1, at the junction of Route 222, there is a store that has gas, coffee, and sandwiches. At the same intersection there is a small diner that provides cheap food. It is warm.

( Click on the map to browse )

The primary attractions at the dam are gulls and Bald Eagles. Conowingo is an electricity generation plant. When the turbines are running, large intake valves suck water, and fish, through the dam, providing excellent feeding for piscivorous birds. The generation schedule is erratic because the dam is a secondary facility and only generates when demand is high. There is some generation almost every day, but on some days it is only early in the morning and late in the day. There is a fisherman's catwalk across the front of the dam which is accessible to birdwatchers most days and provides close looks at the feeding birds. On the far side of the dam, where there is no access, there are a large number of rocks where birds loaf. It requires a scope to see those birds well. Birds feeding at the base of the dam during generation are in the air most of the time and are close enough to be viewed with binoculars.

Large numbers of gulls and Bald Eagles are typically present from mid-October through mid-March. The highest numbers of gulls are present from December through February. Some gulls and Bald Eagles are present in all seasons. Also present all year are large numbers of Great Blue Herons, and there is an active heronry in the woods across from the parking lot. The nests are visible from the viewing area and breeding activity can be watched throughout the spring and summer. A few pairs of Black-crowned Night-Herons have bred on the large island immediately below the dam in recent years and they are present year-round. In non-breeding season they tend to congregate during the day in the brush and small trees at the south end of the island. Careful searching with a telescope usually results in the discovery of at least some of the birds. Small numbers of other herons are present spring through fall. Terns are occasionally numerous in spring and fall. Waterfowl, especially Common Mergansers, are fairly numerous in winter. Ospreys attempt to nest on the large transmission towers on the island below the dam. Bald Eagles have attempted to nest on the transmission towers on the other side of the river the past several years.

Bald Eagle numbers vary from a half-dozen in summer to 30-40 in winter. It is not unusual to find 20 in a single scan from November through February. While there are larger concentrations elsewhere, Conowingo is considered one of the best places east of the Mississippi River to view Bald Eagles because the birds are nearly always present in good numbers and viewing conditions are excellent. The sun is nearly behind observers all day throughout the year. About one out of three winters a single Golden Eagle is found with the Bald Eagles.

Gulls: The reason most bird watchers go to Conowingo. Numbers begin to build in November with the influx of Ring-billed Gulls. Numbers in some years reach 20,000 by the end of the month. Until January, Ring-billeds typically outnumber Herring Gulls 5-10 to one. Following the advent of colder weather in most years, the ratio changes to one-to-one and in some years the preponderance of birds are Herring Gulls by mid-winter. The pattern is largely dependent on how cold a year it is and how much open water is available to the north of Conowingo. Gull numbers begin to diminish in early March. Between 100-500 Great Black-backed Gulls are present throughout the period. The numbers of Bonaparte's Gulls is highly irregular in fall. In some years numbers in November and December reach 2500, but in many years no more than 100-200 are found.

Rarer gulls: The large concentration has resulted in many rarer species being found.

Lesser Black-backed Gull: Perhaps should be included in the regular list above. They have been found every year (persistent observations at the dam go back more than 14 years) and single-day counts have varied between 1-17. Lesser Black-backed is missed on fewer than five percent of the days between November and February. All ages are seen annually and first-winter birds are fairly frequent. There is a retaining wall in the center of the dam and an adult has been seen sitting on the wall almost every day in winter for at least a decade.

Iceland Gull: Present almost every winter. The high count is 11. Typically 1-4 are found. Most are first-winter birds but every age has been seen.

Glaucous Gull: Present most winters but less numerous and consistent than Iceland. Typically 1-2 are found and the high count is about 5. Almost all are first-winter.

Thayer's Gull: Present in at least half the years. Most years only one is found but the seasonal high is three. Most are first-winter or adult.

Slaty-backed Gull: A gull thought to be a Slaty-backed was seen by several hundred observers over a two-week period in the winter of 1998-99. Uncertainty exists about the range of variation in the species and although photographs and field notes seem to support the identification in many observers eyes, others retain some reservation. It is difficult to absolutely rule out hybrid origin on the basis of the available evidence.

California Gull: Found three times in winter. Probably overlooked because close observation of sitting birds is more difficult.

Common Gull: A single first-winter bird of the European race was reported by multiple observers several winters ago. A second report of a first winter bird, seen and photographed by dozens of people and widely circulated as a Common Gull, is now thought to be a slightly aberrant Ring-billed Gull. Controversy over the identification of the species in first-winter plumage has created uncertainty about the status of the species.

Common Black-headed Gull: Reported about six times. Records span the winter season.

Little Gull: Found twice, both adults with large flocks of Bonaparte's Gulls late in the fall.

Franklin's Gull: Two late fall records, both adults.

Laughing Gull: Scarce but regular in late summer and early winter.
Black-legged Kittiwake: Two records. First-winter birds were found in December and January of 1997 and 1998.
Photo by Les Eastman

Caution: Occurrence of large numbers of birds depends on the availability of fish, primarily gizzard shad. Several years ago a spring flood wiped out the gizzard shad breeding effort and numbers were quite low the following winter, and the high count of gulls was less than 2,000. In good years, with normal fish numbers and cold weather, 25,000+ birds can be found at the base of the dam most days. During the times when there is no generation the birds disperse down river and onto the lake above the dam, to which there is limited access. During the slow period, no more than 5,000 gulls may be present for close observation. In the winter of 1995/96 25,000 gulls were present until a sudden thaw in late January resulted in a tremendous volume of water coming down the river. The floodgates at the dam were opened for several days and there was downstream flooding. Following that event there were virtually no gulls at the dam for the rest of the season. No similar circumstance has occurred in the twelve years of observation.

When there is no generation and gulls are not feeding below the dam, the birds tend to gather in flocks on the rocks directly across from the pavilion, on the rock bars and small islands down river, and on the river (also referred to as the pond and the lake, although it is part of the Susquehanna River) above the dam. It is often possible to observe thousands of gulls from the south end of the parking lot or by walking the trail downriver and scoping from various vantage points. Almost all of the rarer gulls have been seen down river at times, and Franklin's Gulls have only been seen from the south end of the parking lot and from farther down river.

Above the dam.

It has long been a source of frustration that viewing birds above the dam is difficult. The access is limited, but persistent efforts have revealed that large numbers of birds are present fall through spring and that some species considered rare in Harford County are nearly regular there. The Susquehanna River is a major migratory pathway for waterbirds and many stop in the deeper water above the dam but are rarely found on the river below the dam. Locally rare species that have been found above the dam include all three species of scoters, Oldsquaw, Red-throated Loon, Brant, Eared Grebe, Great Cormorant, Parasitic Jaeger, and Pacific Loon. This list is certainly not indicative of the full potential because coverage has been sporadic. Very large concentrations of ducks have been found fall through spring. Common Mergansers can be abundant, when water to the north is frozen, and high counts approach 20,000. Large numbers of Bufflehead, Common Goldeneyes, scaup, and some puddle ducks are also regular.

It is typical for large numbers of gulls to roost directly above the dam when they are not feeding in the tailrace during generation. In addition, thousands of gulls, especially Bonaparte's in season, and Ring-billeds, feed on the river. Large numbers of terns also feed above the dam in spring and fall. Iceland, Glaucous, Thayer's, and Lesser Black-backed have been seen above the dam, and Common Black-headed has been seen on several occasions feeding with the Bonaparte's.

Access is a significant problem. On the Harford County side of the river, which is the same side as the parking lot at the dam, there are two spots. The first is close to the dam and viewing conditions are somewhat limited. The access is from the extreme left-hand end of the parking lot at the visitor's center on the north side of Rt. 1, about 100 yards south of Shuresville Road. Enter the parking lot and stay to the left and proceed to the bottom of the lot, next to the small maintenance shed. From the corner of the parking lot you will find a trail down the hill through the woods. It is about 75 yards to the edge of the river and a small promontory. From this spot it is possible to scope up and down the river and the light is always good.

The second spot requires some walking. From the visitor's center parking lot, go south on Rt. 1 (away from the dam) for about one half mile until you see a yellow gate on your right near the top of the next hill. Park on the side of the road. (DO NOT BLOCK THE GATE!) Walk around the gate and follow the access road for about one half mile. The access road goes to a large warning sign for boaters. In front of the sign, there is an extensive view up river and the light is always good.

The best access to the river is from the Cecil County side of the river. Cross the dam on Rt. 1 and go to the top of the hill and the traffic light at Rt. 222. Turn left and go about 1 mile to a left turn (the first left) at Mt. Zoar Road. Follow the road to the small boat launch. The boat launch is in the mouth of the creek and access to the river here is poor, requiring clambering over rocks to get to the railroad tracks. Drive past the boat launch and cross the old metal bridge. The road immediately turns back to the river. After one-half mile you will see a pull over on the left, with room for two or three cars. The pullover is the entrance to the old access road to the railroad tracks but is now blocked by a concrete barrier. Walk around the barrier and down to the railroad tracks, about 100 feet.
(** This note added January 2009 **) The section of Bell Manor Road that leads to the overlook is closed and my never be reopened. It is closed from the boat ramp at the end of Mt. Zoar Road to just below the entrance to the Girl Scout Camp, blocked off with concrete jersey barriers. It is possible to park the car at either end and walk to the overlook. However, it's not exactly a safe area to go walking around in, and it is not recommended that people park and walk unless they are in groups.

The railroad tracks run along the river for the entire Maryland portion, providing excellent views. The disadvantage is that the light is often poor and you will be looking into the sun at some angles. The advantage is that with a viewing field of almost 180 degrees, at least half the river will be in decent to excellent light. You can walk either north as far as the Pennsylvania line or south as far as the dam. Just north of this access, and across the river, is the mouth of Glen Cove and large numbers of gulls and terns frequently feed there. Many will be on the other, inaccessible side of the river and require a scope, but there will rarely be a shortage of birds to look at in any season except summer. It is from this location that the Parasitic Jaeger and the Pacific Loon were observed.

The conditions that produce the best birds are northeast winds and occasional rain from mid-October through November. It is under these conditions that scoters, Brant, and Red-throated Loons are most frequently seen, and accounts for the only jaeger record, a single Parasitic harassing gulls. It was also under those conditions that more than 700 Red-throated Loons were found on one day, the highest inland count in the history of the state.

Other species:.

Shorebirds: Conowingo Dam is one of the best places to find shorebirds in Harford County, more of a testament to the lack of habitat here than to the good numbers at the dam. In late summer and fall, on days when there is little or no generation, shorebirds can be found on the rock bars below the large island opposite the parking lot. Often this requires walking the trail down river from the parking lot. Numbers are never large but persistent searching over the past five years has turned up a good list, including American Golden-Plover, Short-billed Dowitcher, Ruddy Turnstone, Stilt Sandpiper, Dunlin, White-rumped Sandpiper, Wilson's Phalarope, and Sanderling. The birds are often difficult to find in the rocks and the effort requires a good scope.

Waterfowl: The river holds good numbers of ducks fall through spring. The birds most frequently found below the dam are Mallard, Black Duck, Common Goldeneye, and Bufflehead. They are scattered the length of the river and the largest numbers are frequently found by walking the trail at the south end of the parking lot. A favorite spot for puddle ducks is in the rocks directly across from the base of the dam. Except when the water is extremely high, there are always Mallards and Black Ducks there, and it is common to find other species mixed in, especially Northern Pintail, American Wigeon, Green-winged Teal, and Gadwall. All of the regularly occurring puddle ducks have been found. Hooded Mergansers favor this area also. All of the regularly occurring diving ducks have been found below the dam and Common Mergansers move from above to below all day in winter. Red-breasted Mergansers are regular but scarce above and below the dam in migration and winter. A Harlequin Duck spent time around the rocks and the large island one winter and another was seen in early spring. Canada Geese are fairly common above and below the dam at all seasons. Four swans, at least one of which was a Trumpeter, spent much of the winter of 1998-99 in the river below the dam, occasionally moving above the dam or farther down river. They were most frequently seen in the rocks directly across from the pavilion. Like all the waterfowl that favored the rocks, they were sometimes hard to find and viewing birds there requires a good scope. Although no bands were seen, it is possible the birds originated from the ongoing release programs in the eastern Great Lakes.

Other goodies: A fair list of non-gull rarities has been reported from the dam and the trail below the parking lot. A sampling includes: Brown Pelican, Harlequin Duck, Great Cormorant, Mississippi Kite, Yellow-crowned Night-Heron, Royal Tern, Peregrine Falcon, Olive-sided Flycatcher, Common Raven, Western Tanager, Mourning Warbler, and Lincoln's Sparrow. Both Eastern Screech-Owl and Great Horned Owl nest along the river and can be heard at dusk and dawn some days. One to two Peregrine Falcons have spent the winter at the dam since 1997-98. They are most frequently seen sitting in the superstructure on top of the dam or chasing and catching Rock Doves in front of the dam. When not actively hunting, they can be very difficult to pick out.

Spring and fall: The trail below the parking lot in an excellent place to look for flocks of migrants in the spring and fall. Large numbers of warblers, vireos, and flycatchers have been found on some days. Huge swallow flocks begin forming in late summer, sometimes exceeding 10,000. Careful scrutiny has turned up one or two Cliff Swallows every fall.

Summer: Great Blue Herons nest in the woods across from the parking lot. Prothonotary Warblers are numerous on the trail below the dam. Warbling Vireos are common nesters, as are Eastern Kingbird, Orchard and Baltimore Orioles, Northern Parula, and other riparian species. Wild Turkeys nest in the woods south of the dam and are heard on occasion. The same is true for Pileated Woodpecker.

Terns: Numbers begin to build in late summer. Large numbers of Forster's Terns can be seen in the spring and fall and fall numbers can exceed 1000 some years. A few Common Terns are found every fall and spring. Black Tern has appeared in very small numbers most falls. Least Tern has been found once. Caspian Terns are regular in spring and fall. Royal Tern, rare this far north in the Bay and inland, has been recorded once in the fall.

Cormorants: Large numbers of Double-crested Cormorants can now be found in all but the coldest months. They have increased substantially in the past decade and counts now regularly exceed 500 in the fall. In late fall Great Cormorant has been found the past four years in the flocks of Double-cresteds. It is anticipated that nesting by Double-crested, in the Great Blue Heron colony, is only a matter of time.

Future highlights: There are a number of birds that observers have anticipated at the dam but that have not yet been recorded. All the gulls that have been recorded in Maryland except for Yellow-legged, Ross', Black-tailed, and Sabine's have been found and Sabine's is definitely on the watch list. So is the North American race of Common Gull (Short-billed Gull). It has also surprised observers that there is only one jaeger record and it is assumed more will be found eventually. In an invasion year the dam is a fine place for a Snowy Owl to take up residence. Rarer birds that are on the watch list include Arctic Tern, Barrow's Goldeneye, Ivory Gull, Gull-billed Tern, American Oystercatcher, White Pelican, King Eider, and Sandwich Tern. All have some history in the upper Bay or north of the dam in Pennsylvania.

Coverage: There are gullwatchers at the base of the dam nearly every Saturday and Sunday from November through February. Coverage during the week is irregular, as is coverage at other times of the year. Eagle watchers are present nearly every weekend throughout the year. They rarely pay attention to the other birds but sometimes are familiar with what has been reported recently. Good birds found at the dam appear on the Baltimore, Washington, Philadelphia, and Central Pennsylvania hot lines.

More information about the status of birds is available on this web site at the Annotated Checklist of the Birds of Conowingo Dam.


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