The Chesapeake Bay: A Troubled History Of Pollution

The Chesapeake Bay is the United States' largest estuary and has been on the Environmental Protection Agency's (EPA) dirty waters list for decades. Nitrogen, phosphorus, and sediment are the three main sources of pollution in the bay. Nitrogen and phosphorus are nutrients that cause algae blooms, which block sunlight from reaching underwater plants and create low-oxygen dead zones that suffocate marine life. Sediment, which includes loose particles of clay, silt, and sand, also blocks sunlight and smothers bottom-dwelling animals like oysters. These pollutants enter the bay through agricultural runoff, wastewater treatment plants, air pollution, and urban and suburban runoff. Efforts to restore the bay have been made, including the federal Clean Water Act (CWA) and the Chesapeake 2000 agreement, but the bay received a D+ grade in a 2023 report, indicating that more work is needed to reduce pollution and improve water quality.

Nitrogen, phosphorus, and sediment pollution

Nitrogen and phosphorus are nutrients that fuel the growth of algae blooms, which block sunlight from reaching underwater plants and grasses. These algae blooms also deplete the water of oxygen, creating "'dead zones" where fish and shellfish cannot survive. The majority of nitrogen and phosphorus pollution comes from sewage treatment plants, animal feedlots, and polluted runoff from farmland, urban, and suburban areas.

Sediment, on the other hand, includes loose particles of clay, silt, and sand that wash into the water, making it cloudy and blocking sunlight from reaching plants. As it settles, sediment smothers bottom-dwelling animals such as oysters. Sediment can also carry high concentrations of phosphorus and toxic chemicals. While some sediment occurs naturally, human activities such as loose soil and fertilizer use in urban and suburban areas, as well as soil erosion on agricultural property, contribute to sediment pollution.

Excessive amounts of nitrogen, phosphorus, and sediment in the Chesapeake Bay are due to haphazard development, which has stripped the watershed of its natural buffers. As a result, pollution flows undiluted into the waterways. The Chesapeake Clean Water Blueprint outlines the maximum amount of these pollutants that can enter the bay while still allowing it to be removed from the "dirty waters" list.

Efforts to reduce nitrogen, phosphorus, and sediment pollution in the Chesapeake Bay are ongoing. The Chesapeake Bay Program has set goals and implemented best management practices to reduce pollution levels. As of 2023, practices put in place have achieved 57% of the nitrogen reductions and 67% of the phosphorus reduction needed by 2025. Additionally, the agricultural sector has played a significant role in reducing pollution, with a 43% reduction in nitrogen and a 26% reduction in phosphorus.

Agricultural runoff and wastewater treatment

The Chesapeake Bay has been on the Environmental Protection Agency's (EPA) "dirty waters" list for decades. The three main sources of pollution to the bay are nitrogen, phosphorus, and sediment. While nitrogen occurs naturally in soil, animal waste, plant material, and the atmosphere, phosphorus and sediment pollution are largely caused by agricultural runoff and wastewater treatment.

Agricultural practices have a significant impact on the bay's health. Agriculture is the largest source of nutrient and sediment pollution entering the bay. Livestock manure and poultry litter, used as fertilizers, can contaminate waterways when improperly managed. When excess litter is applied to the land, or large amounts are improperly stored, nutrients and bacteria can be carried by runoff into rivers and streams or seep into groundwater. According to the Environmental Protection Agency, manure accounts for 19% of nitrogen and 26% of phosphorus pollution in the bay. Conservation practices, such as nutrient management planning, conservation tillage, and manure storage areas, can help reduce agricultural runoff.

Fertilizers and pesticides are other agricultural sources of pollution. Their excessive use can push nutrients and sediments into waterways, causing harm to marine life. The Chesapeake Bay Program has noted improvements in agricultural practices, with a reduction in nitrogen, phosphorus, and sediment inputs since 2009.

Wastewater treatment plants are another major source of pollution. Human waste treated and discharged from municipal wastewater treatment plants and industrial facilities contribute to the phosphorus pollution in the bay. In 2005, new permit processes were implemented to limit the amount of nutrients these plants could discharge. As a result, nitrogen and phosphorus loads from these sources have significantly declined since 1985.

To address the issue of polluted waterways, the federal Clean Water Act (CWA) requires states to identify and list impaired waters. The Chesapeake Bay and its rivers and streams are on this impaired waters list due to pollution and reduced oxygen levels, which have detrimental effects on aquatic life. Under the CWA, the EPA sets limits on pollutants and develops strategies for restoration. In 2010, President Obama issued an Executive Order, recognizing the Chesapeake Bay as a "national treasure" and instructing the EPA to take specific actions to reduce pollution and improve water quality.

Air pollution from vehicles and power plants

Air pollution is a major contributor to the poor health of Chesapeake Bay. The Chesapeake Bay watershed is affected by the "airshed" that surrounds it, as airborne pollutants fall onto the land and into the water. The four sources of air pollution in the Chesapeake Bay region are stationary and area sources, mobile sources, agricultural sources, and natural sources.

Stationary sources include power plants, manufacturing facilities, and chemical or industrial facilities. Power plants are a significant source of air pollution, releasing pollutants such as nitrogen oxides, sulfur dioxide, and mercury into the atmosphere. These pollutants can travel long distances and eventually fall back to Earth, polluting the land and water and damaging the Bay's ecosystem.

Mobile sources include vehicles such as cars, trucks, boats, airplanes, and off-road vehicles. Vehicle exhaust contributes to air pollution by releasing pollutants into the atmosphere through the burning of fuel, especially when using fuel with a high sulfur content. Additionally, gas-powered lawn tools and construction equipment fall under this category.

Agricultural sources include farm operations that emit gases, chemicals, or particulate matter. Farms are a significant source of nutrient pollution, and the use of chemical fertilizers and manure can lead to increased phosphorus and nitrogen levels in the Bay.

Natural sources of air pollution include lightning and dust storms. While these sources are not human-induced, wind and weather can carry these airborne pollutants over short or long distances, impacting the Bay's airshed.

To address air pollution from vehicles and power plants, regulations and improved technologies are being implemented to reduce emissions. Maintaining and preserving forests is also crucial, as trees act as natural absorbers and traps for airborne pollutants, helping to reduce the amount of pollution that reaches the Bay.

Chemical contaminants and algal blooms

The Chesapeake Bay, the largest estuary in North America, has been facing the issue of chemical contaminants for decades. These contaminants, along with other factors, have contributed to algal blooms in the bay, causing harm to marine life and humans.

Chemical Contaminants

The bay has been impacted by human activities such as agriculture, development, energy production, industry, mining, and transportation. These activities have resulted in the release of nutrients, pesticides, metals, and industrial, personal care, and household chemicals into the watershed. The Chesapeake Bay Foundation identifies nitrogen, phosphorus, and sediment as the three major contributors to the poor health of the bay.

Nitrogen occurs naturally in soil, animal waste, plant material, and the atmosphere. However, excessive amounts of nitrogen, along with phosphorus, enter the bay through fertilizers, wastewater, septic tank discharges, air pollution, and runoff from farms, cities, and suburbs. Phosphorus also enters the bay through manure, emissions, and chemical fertilizers from farmland and animal operations.

Algal Blooms

The nutrients, nitrogen, and phosphorus contribute to the growth of algae. High levels of these nutrients cause excessive algae growth, known as algal blooms. These blooms block sunlight from reaching underwater plants and grasses, which need it to survive. When the algae die, they are decomposed by bacteria, which consume the oxygen in the water, creating low-oxygen areas called dead zones.

The Chesapeake Bay's dead zone, a low-oxygen area, can smother underwater life, including fish and oysters. In September 2024, seasonal temperature changes, polluted water, algal blooms, and dead zones resulted in approximately 24,000 dead fish in Baltimore Harbor.

Harmful algal blooms (HABs) can produce toxins that negatively impact fish, shellfish, and human health. Certain algal species can cause severe vomiting, diarrhea, and abdominal pain in humans after the consumption of contaminated shellfish.

The understanding of the factors triggering the release of algal toxins is limited, and more research is needed to comprehend the pathways of exposure and the risks associated with these harmful algal blooms.

Climate change and government inaction

Chesapeake Bay is the nation's largest estuary and one of the most economically significant regions of the United States. The bay's biologically diverse ecosystem has seen sharp declines in some of its keystone species, including the native oyster. The three main sources of pollution to the Chesapeake Bay are nitrogen, phosphorus, and sediment.

Climate Change

Climate change is affecting the bay, adding more stress to an already unbalanced system. The bay region is facing higher temperatures and rising sea levels that threaten bay recovery, the economy, and the way of life. The number of intense storms is on the rise, bringing more pollution and freshwater into the bay. Heavy storms increase soil erosion, sewer overflows, flooding, and polluted runoff, dumping nitrogen, phosphorus, and sediment into rivers and the bay. As a result, the waters experience more dead zones and algal blooms.

Warming water temperatures have been recorded in more than 92% of the bay's waters. Warmer waters are less able to hold oxygen, leading to a rise in the dead zones that suffocate marine life. The bay's waters have risen about one foot in the past century and are predicted to rise another 1.3 to 5.2 feet over the next 100 years.

Government Inaction

The federal Clean Water Act (CWA) requires states to identify polluted waterways and list them as "impaired." The Chesapeake Bay has been on the EPA's "dirty waters" list for decades. In 2010, under an Executive Order from President Obama, the EPA set limits on nitrogen, phosphorus, and sediment pollution for the bay's watershed. The states are accountable for creating and implementing plans to achieve those limits by 2025.

Despite this, environmental groups have filed lawsuits against the EPA for failing to require Virginia to develop a formal cleanup plan (Total Maximum Daily Load, or TMDL) for its tidal waters on the “dirty waters" list. In response, the EPA and bay jurisdictions signed the Chesapeake 2000 agreement, setting a goal of improving water quality sufficiently to get the bay off the "dirty waters" list by 2010. However, the bay remains polluted, and restoration efforts continue.

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