Nutrient pollution

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Nutrient pollution caused by Surface runoff of soil and fertilizer during a rain storm Runoff of soil & fertilizer.jpg
Nutrient pollution caused by Surface runoff of soil and fertilizer during a rain storm

Nutrient pollution, a form of water pollution, refers to contamination by excessive inputs of nutrients. It is a primary cause of eutrophication of surface waters (lakes, rivers and coastal waters), in which excess nutrients, usually nitrogen or phosphorus, stimulate algal growth. [1] Sources of nutrient pollution include surface runoff from farm fields and pastures, discharges from septic tanks and feedlots, and emissions from combustion. Raw sewage is a large contributor to cultural eutrophication since sewage is high in nutrients. Releasing raw sewage into a large water body is referred to as sewage dumping, and still occurs all over the world. Excess reactive nitrogen compounds in the environment are associated with many large-scale environmental concerns. These include eutrophication of surface waters, harmful algal blooms, hypoxia, acid rain, nitrogen saturation in forests, and climate change. [2]

Contents

Since the agricultural boom in the 1910s and again in the 1940s to match the increase in food demand, agricultural production relies heavily on the use of fertilizers. [3] Fertilizer is a natural or chemically modified substance that helps soil become more fertile. These fertilizers contain high amounts of phosphorus and nitrogen, which results in excess amounts of nutrients entering the soil. Nitrogen, phosphorus and potassium are the "Big 3" primary nutrients in commercial fertilizers, each of these fundamental nutrients play a key role in plant nutrition. [4] When nitrogen and phosphorus are not fully utilized by the growing plants, they can be lost from the farm fields and negatively impact air and downstream water quality. [5] These nutrients can eventually end up in aquatic ecosystems and are a contributor to increased eutrophication. [6] When farmers spread their fertilizer, whether it is organic or synthetically made, some of it will leave as runoff and can collect downstream generating cultural eutrophication. [7]

Mitigation approaches to reduce nutrient pollutant discharges include nutrient remediation, nutrient trading and nutrient source apportionment.

Sources

Agriculture is the major source of nutrient pollution in the Gulf of Mexico. In the Chesapeake Bay, agriculture is a major source, along with urban areas and atmospheric deposition. Nutrient sources Gulf-Mex & Chesbay - EPA 2010.png
Agriculture is the major source of nutrient pollution in the Gulf of Mexico. In the Chesapeake Bay, agriculture is a major source, along with urban areas and atmospheric deposition.
Mean eutrophying emissions (measured as
phosphate equivalents) of different foods [8]
Food typesEutrophying emissions
(g PO43-eq per 100g protein)
Beef
365.3
Farmed fish
235.1
Farmed crustaceans
227.2
Cheese
98.4
Lamb and mutton
97.1
Pork
76.4
Poultry
48.7
Eggs
21.8
Groundnuts
14.1
Peas
7.5
Tofu
6.2
An example in Tennessee of how soil from fertilized fields can quickly turn into runoff creating a flux of nutrients that flows into a local water body NRCSTN83003 - Tennessee (6251)(NRCS Photo Gallery).jpg
An example in Tennessee of how soil from fertilized fields can quickly turn into runoff creating a flux of nutrients that flows into a local water body

The principal source(s) of nutrient pollution in an individual watershed depend on the prevailing land uses. The sources may be point sources, nonpoint sources, or both:

Nutrient pollution from some air pollution sources may occur independently of the local land uses, due to long-range transport of air pollutants from distant sources. [10]

In order to gauge how to best prevent eutrophication from occurring, specific sources that contribute to nutrient loading must be identified. There are two common sources of nutrients and organic matter: point and nonpoint sources.

Nitrogen

Use of synthetic fertilizers, burning of fossil fuels, and agricultural animal production, especially concentrated animal feeding operations (CAFO), have added large quantities of reactive nitrogen to the biosphere. [11] Globally, nitrogen balances are quite inefficiently distributed with some countries having surpluses and others deficits, causing especially a range of environmental issues in the former. For most countries around the world, the trade-off between closing yield gaps and mitigating nitrogen pollution is small or non-existent. [12]

Phosphorus

Phosphorus pollution is caused by excessive use of fertilizers and manure, particularly when compounded by soil erosion. In the European Union, it is estimated that we may lose more than 100,000 tonnes of Phosphorus to water bodies and lakes due to water erosion. [13] Phosphorus is also discharged by municipal sewage treatment plants and some industries. [14]

Point sources

Point sources are directly attributable to one influence. In point sources the nutrient waste travels directly from source to water. Point sources are relatively easy to regulate. [15]

Nonpoint sources

Nonpoint source pollution (also known as 'diffuse' or 'runoff' pollution) is that which comes from ill-defined and diffuse sources. Nonpoint sources are difficult to regulate and usually vary spatially and temporally (with season, precipitation, and other irregular events). [16]

It has been shown that nitrogen transport is correlated with various indices of human activity in watersheds, [17] [18] including the amount of development. [19] Ploughing in agriculture and development are among activities that contribute most to nutrient loading. [9]

Soil retention

Nutrients from human activities tend to accumulate in soils and remain there for years. It has been shown [20] that the amount of phosphorus lost to surface waters increases linearly with the amount of phosphorus in the soil. Thus much of the nutrient loading in soil eventually makes its way to water. Nitrogen, similarly, has a turnover time of decades.

Runoff to surface water

Nutrients from human activities tend to travel from land to either surface or ground water. Nitrogen in particular is removed through storm drains, sewage pipes, and other forms of surface runoff. Nutrient losses in runoff and leachate are often associated with agriculture. Modern agriculture often involves the application of nutrients onto fields in order to maximize production. However, farmers frequently apply more nutrients than are needed by crops, resulting in the excess pollution running off into either surface or groundwater. [21] or pastures. Regulations aimed at minimizing nutrient exports from agriculture are typically far less stringent than those placed on sewage treatment plants [22] and other point source polluters. It should be also noted that lakes within forested land are also under surface runoff influences. Runoff can wash out the mineral nitrogen and phosphorus from detritus and in consequence supply the water bodies leading to slow, natural eutrophication. [23]

Atmospheric deposition

Nitrogen is released into the air because of ammonia volatilization and nitrous oxide production. The combustion of fossil fuels is a large human-initiated contributor to atmospheric nitrogen pollution. Atmospheric nitrogen reaches the ground by two different processes, the first being wet deposition such as rain or snow, and the second being dry deposition which is particles and gases found in the air. [24] Atmospheric deposition (e.g., in the form of acid rain) can also affect nutrient concentration in water, [25] especially in highly industrialized regions.

Impacts

Environmental and economic impacts

Harmful algal bloom in Western Lake Erie on July 9, 2018 Harmful Algal Bloom in Western Lake Erie, July 9, 2018 (41641076380).jpg
Harmful algal bloom in Western Lake Erie on July 9, 2018

Excess nutrients have been summarized as potentially leading to:

Nutrient pollution can have economic impacts due to increasing water treatment costs, commercial fishing and shellfish losses, recreational fishing losses, and reduced tourism income. [28]

Health impacts

Human health effects include excess nitrate in drinking water (blue baby syndrome) and disinfection by-products in drinking water. Swimming in water affected by a harmful algal bloom can cause skin rashes and respiratory problems. [29]

Reduction of discharges

Nutrient trading

Nutrient trading is a type of water quality trading, a market-based policy instrument used to improve or maintain water quality. The concept of water quality trading is based on the fact that different pollution sources in a watershed can face very different costs to control the same pollutant. [30] Water quality trading involves the voluntary exchange of pollution reduction credits from sources with low costs of pollution control to those with high costs of pollution control, and the same principles apply to nutrient water quality trading. The underlying principle is "polluter pays", usually linked with a regulatory requirement for participating in the trading program. [31]

A 2013 Forest Trends report summarized water quality trading programs and found three main types of funders: beneficiaries of watershed protection, polluters compensating for their impacts and "public good payers" that may not directly benefit, but fund the pollution reduction credits on behalf of a government or NGO. As of 2013, payments were overwhelmingly initiated by public good payers like governments and NGOs. [31] : 11 

Nutrient source apportionment

Nutrient source apportionment is used to estimate the nutrient load from various sectors entering water bodies, following attenuation or treatment. Agriculture is typically the principal source of nitrogen in water bodies in Europe, whereas in many countries households and industries tend to be the dominant contributors of phosphorus. [32] Where water quality is impacted by excess nutrients, load source apportionment models can support the proportional and pragmatic management of water resources by identifying the pollution sources. There are two broad approaches to load apportionment modelling, (i) load-orientated approaches which apportion origin based on in-stream monitoring data [33] [34] and (ii) source-orientated approaches where amounts of diffuse, or nonpoint source pollution, emissions are calculated using models typically based on export coefficients from catchments with similar characteristics. [35] [36] For example, the Source Load Apportionment Model (SLAM) takes the latter approach, estimating the relative contribution of sources of nitrogen and phosphorus to surface waters in Irish catchments without in-stream monitoring data by integrating information on point discharges (urban wastewater, industry and septic tank systems), diffuse sources (pasture, arable, forestry, etc.), and catchment data, including hydrogeological characteristics. [37]

Country examples

United States

Agricultural nonpoint source (NPS) pollution is the largest source of water quality impairments throughout the U.S., based on surveys by state environmental agencies. [38] : 10  NPS pollution is not subject to discharge permits under the federal Clean Water Act (CWA). [39] EPA and states have used grants, partnerships and demonstration projects to create incentives for farmers to adjust their practices and reduce surface runoff. [38] : 10–11 

Development of nutrient policy

The basic requirements for states to develop nutrient criteria and standards were mandated in the 1972 Clean Water Act. Implementing this water quality program has been a major scientific, technical and resource-intensive challenge for both EPA and the states, and development is continuing well into the 21st century.

EPA published a wastewater management regulation in 1978 to begin to address the national nitrogen pollution problem, which had been increasing for decades. [40] In 1998, the agency published a National Nutrient Strategy with a focus on developing nutrient criteria. [41]

Between 2000 and 2010 EPA published federal-level nutrient criteria for rivers/streams, lakes/reservoirs, estuaries and wetlands; and related guidance. "Ecoregional" nutrient criteria for 14 ecoregions across the U.S. were included in these publications. While states may directly adopt the EPA-published criteria, in many cases the states need to modify the criteria to reflect site-specific conditions. In 2004, EPA stated its expectations for numeric criteria (as opposed to less-specific narrative criteria) for total nitrogen (TN), total phosphorus (TP), chlorophyll a(chl-a), and clarity, and established "mutually-agreed upon plans" for state criteria development. In 2007, the agency stated that progress among the states on developing nutrient criteria had been uneven. EPA reiterated its expectations for numeric criteria and promised its support for state efforts to develop their own criteria. [42]

After the EPA had introduced watershed-based NPDES permitting in 2007, interest in nutrient removal and achieving regional Total Maximum Daily Load (TMDL) limitations led to the development of nutrient trading schemes. [43]

In 2008 EPA published a progress report on state efforts to develop nutrient standards. A majority of states had not developed numeric nutrient criteria for rivers and streams; lakes and reservoirs; wetlands and estuaries (for those states that have estuaries). [44] In the same year, EPA also established a Nutrient Innovations Task Group (NITG), composed of state and EPA experts, to monitor and evaluate the progress of reducing nutrient pollution. [45] In 2009 the NTIG issued a report, "An Urgent Call to Action", expressing concern that water quality continued to deteriorate nationwide due to increasing nutrient pollution, and recommending more vigorous development of nutrient standards by the states. [46]

In 2011 EPA reiterated the need for states to fully develop their nutrient standards, noting that drinking water violations for nitrates had doubled in eight years, that half of all streams nationwide had medium to high levels of nitrogen and phosphorus, and harmful algal blooms were increasing. The agency set out a framework for states to develop priorities and watershed-level goals for reductions of nutrients. [47]

Discharge permits

Many point source dischargers in the U.S., while not necessarily the largest sources of nutrients in their respective watersheds, are required to comply with nutrient effluent limitations in their permits, which are issued through the National Pollutant Discharge Elimination System (NPDES), pursuant to the CWA. [48] Some large municipal sewage treatment plants, such as the Blue Plains Advanced Wastewater Treatment Plant in Washington, D.C. have installed biological nutrient removal (BNR) systems to comply with regulatory requirements. [49] Other municipalities have made adjustments to the operational practices of their existing secondary treatment systems to control nutrients. [50]

Discharges from large livestock facilities (CAFO) are also regulated by NPDES permits. [51] Surface runoff from farm fields, the principal source of nutrients in many watersheds, [52] is classified as NPS pollution and is not regulated by NPDES permits. [39]

TMDL program

A Total Maximum Daily Load (TMDL) is a regulatory plan that prescribes the maximum amount of a pollutant (including nutrients) that a body of water can receive while still meeting CWA water quality standards. [53] Specifically, Section 303 of the Act requires each state to generate a TMDL report for each body of water impaired by pollutants. TMDL reports identify pollutant levels and strategies to accomplish pollutant reduction goals. EPA has described TMDLs as establishing a "pollutant budget" with allocations to each of the pollutant's sources. [54] For many coastal water bodies, the main pollutant issue is excess nutrients, also termed nutrient over-enrichment. [55]

A TMDL can prescribe the minimum level of dissolved oxygen (DO) available in a body of water, which is directly related to nutrient levels. (See Aquatic Hypoxia.) TMDLs addressing nutrient pollution are a major component of the U.S. National Nutrient Strategy. [56] TMDLs identify all point source and nonpoint source pollutants within a watershed. To implement TMDLs with point sources, wasteload allocations are incorporated into their NPDES permits. [57] NPS discharges are generally in a voluntary compliance scenario. [53]

EPA published a TMDL for the Chesapeake Bay in 2010, addressing nitrogen, phosphorus and sediment pollution for the entire watershed, covering an area of 64,000 square miles (170,000 km2). This regulatory plan covers both the estuary and its tributaries—the largest, most complex TMDL document that EPA had issued to date. [58] [59]

In Long Island Sound, the TMDL development process enabled the Connecticut Department of Energy and Environmental Protection and the New York State Department of Environmental Conservation to incorporate a 58.5 percent nitrogen reduction target into a regulatory and legal framework. [54]

See also

Related Research Articles

<span class="mw-page-title-main">Eutrophication</span> Phenomenon where nutrients accumulate in water bodies

Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of microorganisms that may deplete the oxygen in the water. Eutrophication may occur naturally or as a result of human actions. Manmade, or cultural, eutrophication occurs when sewage, industrial wastewater, fertilizer runoff, and other nutrient sources are released into the environment. Such nutrient pollution usually causes algal blooms and bacterial growth, resulting in the depletion of dissolved oxygen in water and causing substantial environmental degradation.

<span class="mw-page-title-main">Stormwater</span> Water that originates during precipitation events and snow/ice melt

Stormwater, also written storm water, is water that originates from precipitation (storm), including heavy rain and meltwater from hail and snow. Stormwater can soak into the soil (infiltrate) and become groundwater, be stored on depressed land surface in ponds and puddles, evaporate back into the atmosphere, or contribute to surface runoff. Most runoff is conveyed directly as surface water to nearby streams, rivers or other large water bodies without treatment.

<span class="mw-page-title-main">Water pollution</span> Contamination of water bodies

Water pollution is the contamination of water bodies, with a negative impact on their uses. It is usually a result of human activities. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water pollution results when contaminants mix with these water bodies. Contaminants can come from one of four main sources. These are sewage discharges, industrial activities, agricultural activities, and urban runoff including stormwater. Water pollution may affect either surface water or groundwater. This form of pollution can lead to many problems. One is the degradation of aquatic ecosystems. Another is spreading water-borne diseases when people use polluted water for drinking or irrigation. Water pollution also reduces the ecosystem services such as drinking water provided by the water resource.

<span class="mw-page-title-main">Clean Water Act</span> 1972 U.S. federal law regulating water pollution

The Clean Water Act (CWA) is the primary federal law in the United States governing water pollution. Its objective is to restore and maintain the chemical, physical, and biological integrity of the nation's waters; recognizing the responsibilities of the states in addressing pollution and providing assistance to states to do so, including funding for publicly owned treatment works for the improvement of wastewater treatment; and maintaining the integrity of wetlands.

<span class="mw-page-title-main">Agricultural wastewater treatment</span> Farm management for controlling pollution from confined animal operations and surface runoff

Agricultural wastewater treatment is a farm management agenda for controlling pollution from confined animal operations and from surface runoff that may be contaminated by chemicals in fertilizer, pesticides, animal slurry, crop residues or irrigation water. Agricultural wastewater treatment is required for continuous confined animal operations like milk and egg production. It may be performed in plants using mechanized treatment units similar to those used for industrial wastewater. Where land is available for ponds, settling basins and facultative lagoons may have lower operational costs for seasonal use conditions from breeding or harvest cycles. Animal slurries are usually treated by containment in anaerobic lagoons before disposal by spray or trickle application to grassland. Constructed wetlands are sometimes used to facilitate treatment of animal wastes.

<span class="mw-page-title-main">Wastewater quality indicators</span> Ways to test the suitability of wastewater

Wastewater quality indicators are laboratory test methodologies to assess suitability of wastewater for disposal, treatment or reuse. The main parameters in sewage that are measured to assess the sewage strength or quality as well as treatment options include: solids, indicators of organic matter, nitrogen, phosphorus, indicators of fecal contamination. Tests selected vary with the intended use or discharge location. Tests can measure physical, chemical, and biological characteristics of the wastewater. Physical characteristics include temperature and solids. Chemical characteristics include pH value, dissolved oxygen concentrations, biochemical oxygen demand (BOD) and chemical oxygen demand (COD), nitrogen, phosphorus, chlorine. Biological characteristics are determined with bioassays and aquatic toxicology tests.

<span class="mw-page-title-main">Nonpoint source pollution</span> Pollution resulting from multiple sources

Nonpoint source (NPS) pollution refers to diffuse contamination of water or air that does not originate from a single discrete source. This type of pollution is often the cumulative effect of small amounts of contaminants gathered from a large area. It is in contrast to point source pollution which results from a single source. Nonpoint source pollution generally results from land runoff, precipitation, atmospheric deposition, drainage, seepage, or hydrological modification where tracing pollution back to a single source is difficult. Nonpoint source water pollution affects a water body from sources such as polluted runoff from agricultural areas draining into a river, or wind-borne debris blowing out to sea. Nonpoint source air pollution affects air quality, from sources such as smokestacks or car tailpipes. Although these pollutants have originated from a point source, the long-range transport ability and multiple sources of the pollutant make it a nonpoint source of pollution; if the discharges were to occur to a body of water or into the atmosphere at a single location, the pollution would be single-point.

<span class="mw-page-title-main">Surface runoff</span> Flow of excess rainwater not infiltrating in the ground over its surface

Surface runoff is the unconfined flow of water over the ground surface, in contrast to channel runoff. It occurs when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when the soil is saturated by water to its full capacity, and the rain arrives more quickly than the soil can absorb it. Surface runoff often occurs because impervious areas do not allow water to soak into the ground. Furthermore, runoff can occur either through natural or human-made processes.

<span class="mw-page-title-main">DSSAM Model</span> Water quality computer simulation

The DSSAM Model is a computer simulation developed for the Truckee River to analyze water quality impacts from land use and wastewater management decisions in the Truckee River Basin. This area includes the cities of Reno and Sparks, Nevada as well as the Lake Tahoe Basin. The model is historically and alternatively called the Earth Metrics Truckee River Model. Since original development in 1984-1986 under contract to the U.S. Environmental Protection Agency (EPA), the model has been refined and successive versions have been dubbed DSSAM II and DSSAM III. This hydrology transport model is based upon a pollutant loading metric called Total maximum daily load (TMDL). The success of this flagship model contributed to the Agency's broadened commitment to the use of the underlying TMDL protocol in its national policy for management of most river systems in the United States.

A total maximum daily load (TMDL) is a regulatory term in the U.S. Clean Water Act, describing a plan for restoring impaired waters that identifies the maximum amount of a pollutant that a body of water can receive while still meeting water quality standards.

<span class="mw-page-title-main">Best management practice for water pollution</span> Term used in the United States and Canada to describe a type of water pollution control

Best management practices (BMPs) is a term used in the United States and Canada to describe a type of water pollution control. Historically the term has referred to auxiliary pollution controls in the fields of industrial wastewater control and municipal sewage control, while in stormwater management and wetland management, BMPs may refer to a principal control or treatment technique as well.

<span class="mw-page-title-main">Trophic state index</span> Measure of the ability of water to sustain biological productivity

The Trophic State Index (TSI) is a classification system designed to rate water bodies based on the amount of biological productivity they sustain. Although the term "trophic index" is commonly applied to lakes, any surface water body may be indexed.

<span class="mw-page-title-main">Urban runoff</span> Surface runoff of water caused by urbanization

Urban runoff is surface runoff of rainwater, landscape irrigation, and car washing created by urbanization. Impervious surfaces are constructed during land development. During rain, storms, and other precipitation events, these surfaces, along with rooftops, carry polluted stormwater to storm drains, instead of allowing the water to percolate through soil. This causes lowering of the water table and flooding since the amount of water that remains on the surface is greater. Most municipal storm sewer systems discharge untreated stormwater to streams, rivers, and bays. This excess water can also make its way into people's properties through basement backups and seepage through building wall and floors.

<span class="mw-page-title-main">Agricultural pollution</span> Type of pollution caused by agriculture

Agricultural pollution refers to biotic and abiotic byproducts of farming practices that result in contamination or degradation of the environment and surrounding ecosystems, and/or cause injury to humans and their economic interests. The pollution may come from a variety of sources, ranging from point source water pollution to more diffuse, landscape-level causes, also known as non-point source pollution and air pollution. Once in the environment these pollutants can have both direct effects in surrounding ecosystems, i.e. killing local wildlife or contaminating drinking water, and downstream effects such as dead zones caused by agricultural runoff is concentrated in large water bodies.

<span class="mw-page-title-main">Filter strip</span>

Filter strips are strips of permanently vegetated land that are used to reduce the contamination of surface water. They are primarily used in agriculture to control non-point source pollution, however, they may also be used to reduce sediment in storm water runoff from construction sites. There are several types of filter strips including vegetative filter strips, prairie strips and forested riparian buffers. In agriculture, they are highly effective in reducing the concentration of nitrogen (N) and phosphorus (P) in runoff into surface water and are also effective in reducing sediment erosion and removing pesticides. This helps to prevent eutrophication and associated fishkills and loss of biodiversity. The use of filter strips is very common in developed countries and is required by law in some areas. The implementation and maintenance of filter strips is inexpensive and their use has been shown to be cost effective.

<span class="mw-page-title-main">Mississippi River Watershed Conservation Programs</span>

Conservation programs for the Mississippi River watershed have been designed to protect and preserve it by implementing practices that decrease the harmful effects of development on habitats and to overlook monitoring that helps future planning and management. A main focus is nutrient pollution from agricultural runoff of the nation's soybean, corn and food animal production, and problems relating to sediment and toxins. Conservation programs work with local farmers and producers to decrease excess nutrients because they cause major water quality problems along with hypoxia and loss of habitat. Organizations such as the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force and USDA programs such as the Upper Mississippi River Forestry Partnership and the Mississippi River Basin Healthy Watersheds Initiative contribute to conserving what is left of the Mississippi River watershed.

<span class="mw-page-title-main">Water quality law</span>

Water quality laws govern the protection of water resources for human health and the environment. Water quality laws are legal standards or requirements governing water quality, that is, the concentrations of water pollutants in some regulated volume of water. Such standards are generally expressed as levels of a specific water pollutants that are deemed acceptable in the water volume, and are generally designed relative to the water's intended use - whether for human consumption, industrial or domestic use, recreation, or as aquatic habitat. Additionally, these laws provide regulations on the alteration of the chemical, physical, radiological, and biological characteristics of water resources. Regulatory efforts may include identifying and categorizing water pollutants, dictating acceptable pollutant concentrations in water resources, and limiting pollutant discharges from effluent sources. Regulatory areas include sewage treatment and disposal, industrial and agricultural waste water management, and control of surface runoff from construction sites and urban environments. Water quality laws provides the foundation for regulations in water standards, monitoring, required inspections and permits, and enforcement. These laws may be modified to meet current needs and priorities.

<span class="mw-page-title-main">Water pollution in the United States</span> Overview of water pollution in the United States of America

Water pollution in the United States is a growing problem that became critical in the 19th century with the development of mechanized agriculture, mining, and manufacturing industries—although laws and regulations introduced in the late 20th century have improved water quality in many water bodies. Extensive industrialization and rapid urban growth exacerbated water pollution combined with a lack of regulation has allowed for discharges of sewage, toxic chemicals, nutrients, and other pollutants into surface water. This has led to the need for more improvement in water quality as it is still threatened and not fully safe.

<span class="mw-page-title-main">Nonpoint source water pollution regulations in the United States</span>

Nonpoint source (NPS) water pollution regulations are environmental regulations that restrict or limit water pollution from diffuse or nonpoint effluent sources such as polluted runoff from agricultural areas in a river catchments or wind-borne debris blowing out to sea. In the United States, governments have taken a number of legal and regulatory approaches to controlling NPS effluent. Nonpoint water pollution sources include, for example, leakage from underground storage tanks, storm water runoff, atmospheric deposition of contaminants, and golf course, agricultural, and forestry runoff.

<span class="mw-page-title-main">United States regulation of point source water pollution</span>

Point source water pollution comes from discrete conveyances and alters the chemical, biological, and physical characteristics of water. In the United States, it is largely regulated by the Clean Water Act (CWA). Among other things, the Act requires dischargers to obtain a National Pollutant Discharge Elimination System (NPDES) permit to legally discharge pollutants into a water body. However, point source pollution remains an issue in some water bodies, due to some limitations of the Act. Consequently, other regulatory approaches have emerged, such as water quality trading and voluntary community-level efforts.

References

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  19. ↑ Bertness, M. D.; Ewanchuk, P. J.; Silliman, B. R. (2002). "Anthropogenic modification of New England salt marsh landscapes". Proceedings of the National Academy of Sciences of the United States of America. 99 (3): 1395–1398. Bibcode:2002PNAS...99.1395B. doi: 10.1073/pnas.022447299 . JSTOR   3057772. PMC   122201 . PMID   11818525.
  20. ↑ Sharpley AN, Daniel TC, Sims JT, Pote DH (1996). "Determining environmentally sound soil phosphorus levels". Journal of Soil and Water Conservation. 51: 160–166. Archived from the original on 2023-03-30. Retrieved 2021-02-12.
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  22. ↑ Carpenter, S. R.; Caraco, N. F.; Correll, D. L.; Howarth, R. W.; Sharpley, A. N.; Smith, V. H. (August 1998). "Nonpoint Pollution of Surface Waters with Phosphorus and Nitrogen". Ecological Applications. 8 (3): 559. doi:10.2307/2641247. hdl: 1813/60811 . JSTOR   2641247.
  23. ↑ Xie, Meixiang; Zhang, Zhanyu; Zhang, Pingcang (16 January 2020). "Evaluation of Mathematical Models in NitrogenTransfer to Overland Flow Subjectedto Simulated Rainfall". Polish Journal of Environmental Studies. 29 (2): 1421–1434. doi: 10.15244/pjoes/106031 .
  24. ↑ "Critical Loads – Atmospheric Deposition". U.S. Forest Service. United States Department of Agriculture. Retrieved 2 April 2018.
  25. ↑ Paerl H. W. (1997). "Coastal Eutrophication and Harmful Algal Blooms: Importance of Atmospheric Deposition and Groundwater as "New" Nitrogen and Other Nutrient Sources" (PDF). Limnology and Oceanography. 42 (5_part_2): 1154–1165. Bibcode:1997LimOc..42.1154P. doi:10.4319/lo.1997.42.5_part_2.1154. S2CID   17321339.[ permanent dead link ]
  26. ↑ "Harmful Algal Blooms". Nutrient Pollution. EPA. 2020-11-30.
  27. ↑ "National Nutrient Strategy". EPA. 2021-08-18.
  28. ↑ "The Effects: Economy". Nutrient Pollution. EPA. 2022-04-19.
  29. ↑ "The Effects: Human Health". Nutrient Pollution. EPA. 2022-04-19.
  30. ↑ "Frequent Questions about Water Quality Trading". NPDES. EPA. 2022-02-25.
  31. 1 2 Genevieve Bennett; Nathaniel Carroll; Katherine Hamilton (2013). "Charting New Waters, State of Watershed Payments 2012" (PDF). Washington, DC: Forest Trends Association.
  32. ↑ Source apportionment of nitrogen and phosphorus inputs into the aquatic environment. European Environment Agency. Copenhagen: European Environment Agency. 2005. ISBN   978-9291677771. OCLC   607736796.{{cite book}}: CS1 maint: others (link)
  33. ↑ Greene, S.; Taylor, D.; McElarney, Y.R.; Foy, R.H.; Jordan, P. (2011). "An evaluation of catchment-scale phosphorus mitigation using load apportionment modelling". Science of the Total Environment. 409 (11): 2211–2221. Bibcode:2011ScTEn.409.2211G. doi:10.1016/j.scitotenv.2011.02.016. PMID   21429559.
  34. ↑ Grizzetti, B.; Bouraoui, F.; Marsily, G. de; Bidoglio, G. (2005). "A statistical method for source apportionment of riverine nitrogen loads". Journal of Hydrology. 304 (1–4): 302–315. Bibcode:2005JHyd..304..302G. doi:10.1016/j.jhydrol.2004.07.036.
  35. ↑ Mockler, Eva M.; Deakin, Jenny; Archbold, Marie; Daly, Donal; Bruen, Michael (2016). "Nutrient load apportionment to support the identification of appropriate water framework directive measures". Biology and Environment: Proceedings of the Royal Irish Academy. 116B (3): 245–263. doi:10.3318/bioe.2016.22. hdl: 10197/8444 . JSTOR   10.3318/bioe.2016.22. S2CID   133231562.
  36. ↑ Smith, R.V.; Jordan, C.; Annett, J.A. (2005). "A phosphorus budget for Northern Ireland: inputs to inland and coastal waters". Journal of Hydrology. 304 (1–4): 193–202. Bibcode:2005JHyd..304..193S. doi:10.1016/j.jhydrol.2004.10.004.
  37. ↑ Mockler, Eva M.; Deakin, Jenny; Archbold, Marie; Gill, Laurence; Daly, Donal; Bruen, Michael (2017). "Sources of nitrogen and phosphorus emissions to Irish rivers and coastal waters: Estimates from a nutrient load apportionment framework". Science of the Total Environment. 601–602: 326–339. Bibcode:2017ScTEn.601..326M. doi: 10.1016/j.scitotenv.2017.05.186 . hdl: 10197/9071 . PMID   28570968.
  38. 1 2 National Nonpoint Source Program: A catalyst for water quality improvements (Report). EPA. October 2016. EPA 841-R-16-009.
  39. 1 2 "NPDES Permit Basics". EPA. 2021-09-28.
  40. ↑ Kilian, Chris (2010). "Cracking down on Nutrient Pollution: CLF Fights to Bring New England's Coastal Waters Back to Life". Conservation Matters. 16 (2).
  41. ↑ National Strategy for the Development of Regional Nutrient Criteria (Report). EPA. June 1998. EPA 822-R-98-002.
  42. ↑ Grumbles, Benjamin (2007-05-25). "Nutrient Pollution and Numeric Water Quality Standards" (PDF). EPA. Memorandum to State and Tribal Water Program Directors.
  43. ↑ "Permit Limits: Watershed-based Permitting". NPDES. EPA. 2021-10-11.
  44. ↑ State Adoption of Numeric Nutrient Standards (1998–2008) (Report). EPA. December 2008. EPA 821-F-08-007.
  45. ↑ "Programmatic Information on Numeric Nutrient Water Quality Criteria". EPA. 2017-05-16.
  46. ↑ An Urgent Call to Action: Report of the State-EPA Nutrient Innovations Task Group (Report). EPA. August 2009. EPA 800-R-09-032.
  47. ↑ Stoner, Nancy K. (2011-03-16). "Working in Partnership with States to Address Phosphorus and Nitrogen Pollution through Use of a Framework for State Nutrient Reductions" (PDF). EPA. Headquarters Memorandum to EPA Regional Administrators.
  48. ↑ "Status of Nutrient Requirements for NPDES-Permitted Facilities". NPDES. EPA. 2021-09-28.
  49. ↑ "Removing Nitrogen from Wastewater Protects our Waterways". Washington, D.C.: DC Water. Retrieved 2018-01-15.
  50. ↑ "National Study of Nutrient Removal and Secondary Technologies". EPA. 2021-09-22.
  51. ↑ "Animal Feeding Operations". NPDES. EPA. 2021-07-23.
  52. ↑ "Agriculture". Learn the Issues. Annapolis, Maryland: Chesapeake Bay Program. Archived from the original on 2018-10-07. Retrieved 2018-10-06.
  53. 1 2 "Overview of Identifying and Restoring Impaired Waters under Section 303(d) of the CWA". Impaired Waters and TMDLs. EPA. 2021-09-20.
  54. 1 2 "TMDLs at Work: Long Island Sound". EPA. 2021-06-16.
  55. ↑ Golen, Richard F. (2007). "Incorporating Shellfish Bed Restoration into a Nitrogen TMDL Implementation Plan" (PDF). Dartmouth, MA: University of Massachusetts, Dartmouth. Archived from the original (PDF) on 2016-11-16. Retrieved 2013-05-24.
  56. ↑ "National Nutrient Strategy". EPA. 2007.
  57. ↑ "Chapter 6. Water Quality-Based Effluent Limitations". NPDES Permit Writers' Manual (Report). EPA. September 2010. EPA-833-K-10-001.
  58. ↑ "Chesapeake Bay Total Maximum Daily Load". EPA. 2022-04-20.
  59. ↑ Chesapeake Bay TMDL Executive Summary (PDF) (Report). EPA. 2010-12-29.
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