Present-day Reservoirs

        Although impoundments of the Brandywine and its tributaries have declined in abundance, some dams remain as ghosts of another age (Fig. 7).

Fig. 7.Bondsville Dam, located on Beaver Creek, northwest of Downingtown.

Twenty-nine dams currently span the Brandywine and its major tributaries in Pennsylvania (Fig. 8). An additional 11 dams impound segments of the main stem in Delaware. These dams, and the impounded water behind them, have important ecological impacts on sediment and nutrient transport within the stream network, raise stream temperatures during the summer, create areas of lower oxygen, replace free-flowing aquatic habitats with still-water habitats and interrupt the stream system’s linear continuity, altering both the upstream and downstream movement of fish.
        The Brandywine Conservancy has extensively studied the possibility of removing or modifying these dams to allow American Shad (Alosa sapidissima) to once more migrate up the Brandywine to spawn.

Fig. 8.Locations of 11 dams spanning the Brandywine Creek in Delaware. Map courtesy of the Brandywine Conservancy.

American shad were once an enormously abundant migratory fish found throughout East Coast rivers and streams, including the Brandywine Creek, and were an important part of both the Native American and early Colonialist diets. Later, they were the basis of the largest commercial fishery on the Susquehanna and Delaware Rivers.
        Working with dam owners, other environmental organizations and technical advisors, the Brandywine Conservancy has developed a set of options for providing fish passage for American shad and other migratory fish for the eleven dams still found today on the mainstem in Delaware and for twelve dams found on the Brandywine River‘s mainstem and the lower East and West Branches in Pennsylvania (Fig. 8).
        The 40 dams found on both the Delaware and Pennsylvania portions of the Brandywine today include 34 “small” dams (“run-of-the-river” dams less than 15’ high), and six large dams (greater than 30’ high). Their combined ecological impact, like that of smaller ponds elsewhere in the watershed, has been changing over time. Whereas most ponds are proliferating, however, the long term prognosis for reservoirs in the watershed is likely one of continued decline. For additional information about individual dams, and the had restoration initiative, see Brandywine Conservancy