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Report on the Environment

Recreation in and on the Water

What are the trends in the condition of recreational waters and their effects on human health and the environment?

The nation’s rivers, lakes, and coastal waters are used for many different forms of recreation. Some recreational activities take place in or on the water, such as swimming, boating, whitewater rafting, and surfing. Other activities may not involve contact with the water yet may still require water—or be enhanced by proximity to water. Examples include a picnic at the beach, hiking, nature viewing (e.g., bird watching), and hunting (especially waterfowl). People also engage in fishing and shellfishing as recreational activities.

In the questions on fresh surface waters and coastal waters, condition is defined as a combination of physical, chemical, and biological attributes of a water body. For recreational waters, condition is more specific, focusing on those physical, chemical, and biological attributes that determine a water body’s ability to support recreational activities. The particular attributes necessary to support recreation vary widely, depending on the nature of the activity in question. In a more general sense, however, the components of recreational condition fall into two main categories:

  • Attributes that determine whether recreational activities can be enjoyed without unacceptable risk to human health—primarily pathogens and chemical contaminants that can affect the health of humans who are exposed during contact activities such as swimming.

  • Attributes associated with ecological systems that support recreation—e.g., the status of fish and bird communities, as well as chemical and physical characteristics that may affect these populations and their habitat. These attributes also contribute to the aesthetic qualities important for recreational activities.

Many stressors affecting the condition of recreational waters fall into the broad category of contaminants. This category includes chemical contaminants, various pathogens (viruses, bacteria, and other parasites or protozoans) that can cause infectious disease, and pollutants such as trash or debris. These stressors can come from a variety of point sources and nonpoint sources, and can be discharged or washed directly into recreational waters or carried downstream to lakes or coastal areas. Among the major sources are storm water and sediment runoff, direct discharge (e.g., from industrial facilities and sewer systems), atmospheric deposition, and recreational activities themselves (e.g., outboard motor exhaust and overboard discharge of sanitary wastes). Some chemicals and pathogens occur naturally, but their abundance may be influenced by other human stressors such as land use and land cover (e.g., paved surfaces and forestry and irrigation practices, which can influence runoff patterns) or by natural stressors such as weather and climate. Land use and land cover can influence recreational condition in other ways as well.

In terms of human health, the stressors that pose the greatest potential risks are chemical and biological contaminants. People can be exposed to these contaminants if they swim in contaminated waters or near storm water or sewage outfall pipes—especially after a rainfall event. Boating also may pose risks of exposure, although to a lesser extent. For toxic chemical contaminants, the main routes of exposure are through dermal (skin) contact or accidental ingestion. For pathogens, the main route of exposure is by swallowing water, although some infections can be contracted simply by getting polluted water on the skin or in the eyes. In some cases, swimmers can develop illnesses or infections if an open wound is exposed to contaminated water.

Effects of exposure to chemical and biological contaminants range from minor illnesses to potentially fatal diseases. The most common illness is gastroenteritis, an inflammation of the stomach and the intestines that can cause symptoms such as vomiting, headaches, and diarrhea. Other minor illnesses include ear, eye, nose, and throat infections. While unpleasant, most swimming-related illnesses are indeed minor, with no long-term effects. However, in severely contaminated waters, swimmers can sometimes be exposed to serious and potentially fatal diseases such as meningitis, encephalitis, hepatitis, cholera, and typhoid fever.28 Children, the elderly, and people with weakened immune systems are most likely to develop illnesses or infections after coming into contact with contaminated water.

From an ecological perspective, stressors to recreational waters can affect habitat, species composition, and important ecological processes. For example, changes in land cover (e.g., the removal of shade trees) may cause water temperature to rise above the viable range for certain fish species. Hydromodifications such as dams may create some recreational opportunities (e.g., boating), but they also may impede the migration of fish species such as salmon. Chemical and biological contaminants may harm plants and animals directly, or they may disrupt the balance of the food web. For example, acid deposition may lead to acidification in lakes, while excess nutrients can lead to eutrophic conditions such as low levels of dissolved oxygen, which in turn can harm fish and shellfish populations. Beyond their obvious effects on activities like fishing and nature viewing, stressors such as these also can be detrimental to recreational activities in a more aesthetic sense, as the presence of dead fish or visibly unhealthy plants may diminish one’s enjoyment of recreation in or near the water.

Ultimately, ecological effects can also impact human health. For example, eutrophic conditions can encourage harmful algal blooms—some of which can produce discomfort or illness when people are exposed through ingestion or skin or eye contact. One well-known type of harmful algal bloom is “red tide,” which in humans can cause neurotoxic shellfish poisoning and respiratory irritation.29

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