What are some examples of nonpoint source?

Answer 1

Nonpoint source pollution is pollution that is caused by diffuse sources and can negatively affect waterways such as rivers, lakes, wetlands, and estuaries. Nonpoint source (NPS) pollution is the leading cause of water quality problems and is occurs when rainfall or snowmelt picks up pollutants as it moves over land or through the ground and then deposits then in water sources. Nonpoint source pollution can occur in an urban or a rural setting and each area presents its own unique circumstances. A mitigation plan for nonpoint source pollution would need to address the specifics in each setting.

Unlike point source pollution, the direct cause of nonpoint source pollution cannot be identified in terms of the pollution coming from one distinct source. The diffuse sources, depending on location, may include pollutants such as excess herbicides, insecticides, and fertilizers, sediment, salt, bacteria and nutrients, oil, grease, and toxic chemicals. The result of these pollutants being deposited into various water sources can be beach closures, the destruction of habitat, fish kills, and unsafe drinking water, among other things. The most common pollutants in terms of nonpoint source pollution are sediment and nutrients (EPA, 2009).

Because NPS pollution is the leading cause of water quality problems, the United States Environmental Protection Agency has conducted extensive studies to quantify the NPS problem. Approximately 40% of the surveyed estuaries, lakes, and streams were determined to be not fit to meet even the most basic of uses such as fishing and swimming. Of the surveyed estuaries, urban runoff was determined to be the largest source of water quality problems. Urban runoff often includes oils, grease, and toxic chemicals that are washed from impervious surfaces such as roads into the waterways and on to the receiving waterbodies. Agricultural runoff is determined to be the cause of pollution in 60% of the surveyed river miles that are classified as impaired and in 50% of the impaired lake acreage. In addition to the fertilizers and chemicals that are applied to agricultural lands, soil erosion also contributes to the pollution problem because of the increase in sediment load (EPA, 2009).

Residential areas present their own form of problems with NPS pollution. Septic tanks that are not properly functioning can contribute to the addition of bacteria and nutrients. Also, fertilizers and pesticides that are not applied in the proper manner can result in excess product reaching receiving waterbodies as well. In addition, the improper use, storage, and disposal of household chemicals can contribute to water pollution. One of the major challenges with addressing NPS pollution is determining what potential sources are contributing to the problem (EPA, 2009).

NPS pollution is a problem that can be addressed on many levels. On the federal level, programs such as the Nonpoint Source Pollution Management Program are meant to address the NPS pollution problem. This act was established in 1987 by the Clean Water Act Amendments. The Coastal Nonpoint Source Pollution Program was established in 1990 by the Coastal Zone Act Reauthorizing Amendments. Other ways the federal government can take responsibility for NPS pollution is to ensure that federal lands are managed for soil erosion, logging, and pesticide application (EPA, 2009).

States can take responsibility for NPS pollution by enacting legislation that enforces the use of best management practices in industries such as mining and logging to reduce the impact of those industries on the water resources. Locally, ordinances can be passed for zoning as well as erosion control. Individuals can also be responsible for their part in NPS pollution by practicing conservation and by changing some habits regarding landscaping and the use of household chemicals.

On the east coast of the United States, an estimated 285 million pounds of nitrogen reach the Chesapeake Bay each year. Excess nitrogen can lead to problems such as algal blooms. When algae decompose, they deplete the water body of oxygen and can result in 'dead zones' that disrupt the aquatic food web. In 2002, the states that contribute to Chesapeake Bay sought federal support to reduce the amount of nitrogen that was reaching this important estuary. The states asked for $20 million to test four new farm practices that could reduce the runoff from agricultural lands by 50%. The anticipated reduction in nitrogen loading would be about 6 million pounds per year. One of the programs suggested by the states was to pay farmers to use fewer nutrients on their crops and to plant cover crops to reduce soil erosion (Blankenship, 2002).

In 2008, Virginia and Maryland introduced another program aimed at reducing runoff from agricultural land. This came as a result of a study that estimated that 42% of the nitrogen, 46% of the phosphorus, and 72% of the sediment that was reaching Chesapeake Bay came from agricultural lands. Virginia proposed spending $20 million to implement best management practices aimed at improving water quality. The main components of the plan included building buffers around agricultural fields, keeping cattle out of creeks and rivers, and coming up with improved methods of fertilizer storage. In Maryland, state officials proposed the Cover Crop Program to reduce sediment loading from soil erosion as one of their strategies. Chicken farms are a large business in Maryland and presents unique problems. A manure management plan was proposed as well, but the enforcement of manure management remains a problem (Kelleher, 2008).

In Florida where the water table tends to be high and canals and ditches are common, nonpoint source pollution is a serious problem for the state's waterways. In an effort to reduce the standing water that serves as a habitat for mosquitoes and to provide more land for development, areas in Florida have been ditched to drain the water quickly from inland areas. While this serves its purpose to prevent flooding and reduce the mosquito population, it also serves as a conduit for nonpoint source pollution to reach important estuaries and other waterways. The EPA originally set a deadline of 2004 for Florida to establish limits on the amount of nutrients that reach these waterways. Florida essentially disregarded the order, though many local governments have enacted their own local ordinances to combat the nutrient problem (Earthjustice, 2009).

Fertilizer ordinances such as those in Sarasota County, Florida are designed to prevent excess nutrients from residential application of fertilizer from reaching the coastal waters. To do this, residents are not allowed to apply fertilizer to their lawns from June 1st to September 30th. This is Florida's rainy season when almost daily rainfall would wash many of the nutrients out to receiving water bodies. Fertilizer-free zones were established within 10 feet of water bodies. For those who violate the ordinance, the first offense is a warning followed by a $500 penalty for repeat offenders. The ordinance also established a voluntary 'low-maintenance' zone within 6 feet of water bodies and it recommended the use of slow-release fertilizers (Whittle, 2007). The state has looked at statewide legislation similar to Sarasota County's ordinance, but has been met with some resistance from fertilizer companies. The phosphate industry is a large component of the Florida economy and there is concern that restrictions on fertilizer use would impact this market.

The high water table in Florida also presents problems with the use of septic tanks. When properly installed and maintained, septic tanks provide residential waste water treatment. When they malfunction or are installed in a place that does not allow them to function as they should, they can contribute nutrients and bacteria to the NPS pollution problem. Communities across the state are taking actions to replace septic tanks with central sewer in areas where the septic tanks are thought to be contributing to the nutrient loading that causes algal blooms and bacteria that can result in beach closings. Marco Island is one place that has taken steps to increase their central sewer system to reduce the nutrient loading (SFWMD, 2008). The problem with this course of action is that it is often cost prohibitive. There is a cost to the utility for extending the sewer lines and often a cost to homeowners to hook up to the system. In addition, some homeowners are resistant to the idea of paying for central sewer when with septic tank they had no monthly charges. Local ordinances requiring central sewer are one solution to voluntary hook ups that may not have the same participation rate.

The mitigation strategy for NPS pollution would have to have many layers. Beginning at the local level, ordinances could be passed to address the problem. Among the possible local strategies are: requiring new development to have a higher percentage of pervious surfaces to reduce runoff volume; enact fertilizer ordinances to reduce the amount of available nutrients in runoff; require new developments to hook up to central sewer and start septic tank replacement programs; institute public education on the use, storage, and disposal of household chemicals; and, improve stormwater management systems that would lengthen retention time of stormwater runoff and allow removal of some components of NPS pollution.

At the state level, a mitigation plan would include: legislation regarding the use of fertilizers; requirements for buffer zones around agricultural areas; legislation for the storage and disposal of animal waste; grants for homeowners who replace their septic tanks with central sewer connections; and, to provide funding to support local initiatives to reduce urban runoff. At the federal level, support would come in the form of funding to investigate which strategies would work best in certain areas, develop new best management practices, and to provide subsidies for farmers who implement the best management practices.

As with any strategy, the problem with legislation at the local or state level is enforcement. Enacting laws to restrict the use of fertilizers is only the first step to addressing the problem. Finding and penalizing those who ignore the law presents a greater challenge, especially in communities where funds are sometimes in short supply. The benefits of this multi-layered mitigation strategy is the reduction of nonpoint source pollution reaching and harming our water bodies. This protects habitat, areas used for drinking water supply and recreation, and improves the quality of life. Challenges to the plan would come from industries who may be impacted by the reduction of sales in certain products, though the strategy may encourage them to develop products that are more environmentally friendly. The other challenges may come from homeowners who are impacted financially if they are required to replace their septic tanks with central sewer and from homeowners who are resistant to the idea of a government entity telling them when and how much fertilizer they can apply to their lawns.

Whatever the approach, it is obvious that nonpoint source pollution is a serious problem in both rural and urban areas. The pollution can kill fish, destroy important habitat, impact fishing and recreational opportunities, and present a threat to human health. The reduction of runoff, both from urban areas and agricultural lands, will only improve the health of the world's water resources. The mitigation strategies are something that must be pursued in order to stop any further degradation from occurring and before the water resources reach a point where they are permanently impacted.