Eutrophication of Chesapeake Bay: Causes and Solutions

Introduction: A Bay Under Threat

Chesapeake Bay, the largest inlet of the Atlantic Ocean, has been plagued with pollution for hundreds of years. Originally described by Captain John Smith in the early 1600s as having clear water with underwater grasses, oyster reefs, and abundant fish, the Bay today appears on the Environmental Protection Agency's list of impaired waters (Chesapeake Bay Foundation, "Water Pollution in The Chesapeake Bay"). Polluted with nitrogen and phosphorus, among other contaminants, the Bay's inhabitants — both animal and plant — are in severe danger of destruction unless humans intervene with aggressive action. This paper discusses the reasons for the eutrophication of Chesapeake Bay, the consequences of that eutrophication, and possible solutions to the problem.

Located off the coast of Eastern Maryland and Eastern Virginia, Chesapeake Bay stretches 200 miles in length, and its width ranges from four to 40 miles. Many rivers and streams — including the James, York, Rappahannock, Potomac, Patuxent, and Susquehanna rivers — feed into the Bay (Encarta, "Chesapeake Bay"). Home to more than 2,700 species of plant and animal life, including oysters, the blue crab, and over 150 species of fish, the Bay has historically provided settlers and Native Americans with vital natural resources (Virginia Natural Resource Leadership Institute [VNRLI], 1). At its healthiest in the early 1600s, the Bay rated an estimated 100 on a scale of 100 in terms of ecological health, according to the Chesapeake Bay Foundation (Chesapeake Bay Foundation, "2002 State of the Bay Report," 1).

As of 2002, the CBF's Report listed the Bay at 27 — one point lower than in 1999 and 2000 (CBF, "2002 State of the Bay Report," 1). Home to approximately 15 million people (VNRLI, 1), the Bay is a victim of eutrophication, a "condition in an aquatic ecosystem where high nutrient concentrations stimulate blooms of algae" (Environmental Protection Agency, 8). While this type of condition occurs naturally in some cases, human activity in the Bay watershed has historically accelerated the process through pollution (Environmental Protection Agency, 9).

Understanding Eutrophication and Its Ecological Consequences

The increase in certain types of pollution causes algal blooms — large growths of algae whose proliferation interferes with the health and diversity of all living species within the ecosystem. These blooms harm aquatic life in two primary ways. First, large algal blooms block sunlight from penetrating the water, causing underwater grasses to die. The death of these grasses eliminates food and shelter for other creatures that depend on them. Second, as the blooms die and decompose, they consume vital dissolved oxygen, creating hypoxic conditions in which remaining species cannot survive (EPA, 9).

In the Chesapeake Bay area, these large algal blooms have created one of the largest "dead zones" ever recorded (CBF, "CBF Takes Legal Action to Compel EPA to Enforce the Clean Water Act"). Dead zones are areas in which algal decomposition is so extensive that there is literally not enough oxygen for any other species to survive; consequently, all living creatures — both plant and animal — within that zone perish (CBF, "Water Pollution in The Chesapeake Bay"). This type of severe hypoxic activity tends to occur in the Bay below depths of 5 to 10 meters (Bratton, 1).

Under normal conditions, nitrates and phosphorus are essential nutrients for the Bay's organisms. However, as the concentrations of those and other toxins rise, water quality declines. As quality decreases, plant and animal life begins to suffer, and without any intervention, the area would eventually become an entirely lifeless dead zone (Hoagland, "Bay Cleanup Plans Fail to Deliver").

Causes of Pollution in Chesapeake Bay

There are many causes for the eutrophication of Chesapeake Bay, and solving the problem first requires understanding them. The true problem began with the earliest developers of the Bay area. When Captain John Smith first described the Bay, the surrounding landscape had been largely untouched by humans and consisted of protective buffers of forests, open spaces, and wetlands (Chesapeake Bay Foundation, "2002 State of the Bay Report," 1). Once development began, however, disorganized growth stripped the Bay of those buffers, allowing pollution to run freely into the waterways (Chesapeake Bay Foundation, "2002 State of the Bay Report," 2). The forests and open lands have since been replaced by farmland, factories, and cities, which not only erode natural buffers but also directly add to the pollution problem.

Beyond the loss of buffers, farms, factories, and cities produce over 300 million pounds of nitrogen pollution that reaches Chesapeake Bay each year (CBF, "Water Pollution in The Chesapeake Bay"). This amount is more than six times what scientists consider a healthy level for the Bay (Chesapeake Bay Foundation, "2002 State of the Bay Report," 2). In addition, massive amounts of phosphorus, mercury, and other toxins are flushed into the Bay annually (CBF, "Water Pollution in The Chesapeake Bay"). The level of mercury in the Bay in 2002 was three to 18 times the level the EPA considers hazardous (EPA, "Mercury Contamination in the Chesapeake Bay").

The major cause of this pollution is agricultural runoff, which constitutes roughly 40% of the nitrogen pollution in the Bay and approximately 50% of the phosphorus. Maryland's large-scale chicken production operations contribute substantially to these levels. These facilities — mainly located along the Shenandoah and Potomac rivers — house approximately 1,000 chickens per human resident, and chicken waste produces four times the amount of nitrogen and 24 times the amount of phosphorus generated by hog or cattle waste (CBF, "Water Pollution in The Chesapeake Bay").

In addition to agricultural pollution, land-based sources such as power plants, motor vehicles, urban runoff, and municipal sewage treatment plants contribute to rapid eutrophication, as does the use of fertilizers in suburban areas (CBF, "Water Pollution in The Chesapeake Bay"). According to a detailed CBF analysis published in 2002 — Sewage Treatment Plants: The Chesapeake Bay Watershed's Second Largest Source of Nitrogen Pollution — only ten of more than 300 sewage treatment plants in the Bay watershed possessed the technology needed to reduce nitrogen discharges (CBF, "CBF Takes Legal Action to Compel EPA to Enforce the Clean Water Act").

Finally, there are natural contributors to eutrophication in Chesapeake Bay. Seasonal rainfall increases carry nitrates from wetlands and marshes into the Bay through runoff. As spring approaches, longer periods of daylight encourage growth in phytoplankton and algae. As new blooms develop, the remnants of the previous year's blooms die and decompose, depleting dissolved oxygen needed by other organisms. While some degree of this cycling is normal in any aquatic ecosystem, the Bay's rate of eutrophication is far faster than in most comparable areas, owing to the massive quantities of algae already present in the waterway (Williams, 27).

Conclusion: Restoring a National Treasure

The rapid eutrophication of Chesapeake Bay is a tragedy that can be repaired. While the Bay may never be fully restored to its original beauty, as described by Captain John Smith in the early 1600s, there is still hope that it can reclaim its status as the national treasure it once was. The restoration of the Bay to a productive, healthy ecosystem requires improved water clarity, the elimination of toxic contaminants, and the reestablishment of natural buffers (Chesapeake Bay Foundation, "2002 State of the Bay Report," 2). This restoration will require the cooperation of the federal government, local enforcement agencies, local governments, businesses, farms, industries, and individual citizens alike. It is only through adequate funding, rigorous enforcement, and a conscious, committed, and driven collective effort that the Bay can truly be restored.