William G. Thomas III, et. al., The Countryside Transformed

Change in the arrangement and use of the land produced consequent and unexpected (and usually unnoticed) effects. Runoff of sand, clay, and other debris from the roads and of topsoil, fertilizer, and pesticide from the fields led to the silting of the upper reaches of Eastern Shore creeks (though more evident on the seaside than on the bayside where the compensatory effect of sea level rise was more pronounced) and, to varying degrees, the pollution of the lower reaches. Throughout the period the U.S. Army Corps of Engineers dredged the channels of creeks and inlets filled by silt and by sands shifted by current and tide, paddle and propeller. The runoff (and, probably, the dredging) affected adversely water clarity, oxygen content, and the survival of bottom-dwelling plants. It included traces of Paris Green, the potato grower’s pesticide of choice, a deadly compound of arsenic and copper.66

Increases in surface runoff associated with land clearing had changed the proportions of less dense fresh water and more dense salt water that mixed in the Chesapeake Bay, which intensified stratification (and decreased mixing between upper and lower levels in the water column that otherwise would transport oxygen from the surface to the depths). Moreover, an increased nutrient load in the runoff associated with terrestrial fertilizer use had fed algal blooms (a process commonly referred to as "eutrophication"), which blocked light from penetrating the water column and decreased habitat for submerged aquatic vegetation that otherwise would have produced oxygen as a byproduct of photosynthesis. The final assault on bottom water (benthic) oxygen levels in the Bay occurred when the algal blooms would die on a seasonal basis, settle to the bottom, and undergo an oxygen-consuming decay processes. These three developments associated with terrestrial land use (increased runoff and nutrient load, vertical stratification, and eutrophication leading first to decreased light penetration and second to oxygen-consuming decay) caused what is referred to in scientific language as "benthic anoxia" - a growing portion of Chesapeake bottom waters no longer had enough oxygen to support the oysters, crabs, green plants, and other life that had historically thrived in the benthic habitat. The unintended consequences of human land use practices that began with extensive early-eighteenth-century land clearing had changed the ecology of the Chesapeake Bay, the repercussions of which were felt by the watermen of the Eastern Shore in their poor hauls by the 1920s (although not scientifically documented until 1936).67

Throughout the Chesapeake Bay watershed during the late nineteenth century, human influences on the water quality and bay life included not only land use runoff but also drainage of raw sewage, based in large part on logic such as that espoused by Baltimore Sewage Commission when it advised in 1897 that there was “but little reason” not to take advantage of the Bay’s “diluting effect” and to keep dumping sewage. In 1924 a typhoid outbreak linked to tainted oysters arose in Chicago, New York, and Washington in which 1,500 cases of typhoid and 150 deaths were reported, causing major concern to those interested in protecting human health as well as the reputation and economic future of the seafood industry.68

In 1912 Charles Francis Adams, the New England man of letters, recalled a recent visit to the Eastern Shore. Citing Howard Pyle's 1879 essay, Adams noted that Pyle had written "the lifetime of a generation ago." Conditions on the peninsula, Adams continued, had "markedly changed." "The railroads had pushed their way south of the Maryland line and. . . . direct and easy lines of communication have been opened between a region of singular natural productiveness and the largest American markets." Having seen the Eastern Shore in a seeming fever of human activity, Adams concluded that "the Rip Van Winkle sleep has manifestly come to an end."69