Ecosystems provide water resources

• Multiple factors can affect water quality and quantity, including land management, point-source pollution, hydrologic alteration, and invasive speciesinvasive speciesA type of plant, animal, or other organism that does not naturally live in a certain area but has been introduced there, often by people. An invasive species can spread quickly, especially if it has no natural predators in its new home. An invasive species can hurt native species, disrupt ecosystems, and create problems for people (for example, weeds and insects that damage crops)..This eco-wheel image shows the natural resources providing clean and plentiful water, the benefits, and drivers of change. 
• Point-source pollution enters water directly from factories, power plants, and other stationary sources. Non-point source (NPS) pollution is pollution that runs into water from agricultural lands, impervious surfaces, or other land uses.
• In the 2000 National Water Quality Inventory, agricultural NPS pollution was reported to be the leading source of water quality impairment in surveyed lakes and rivers². Forestry practices also significantly affect water quality by increasing the amount of sediment that gets deposited into local water bodies.
• Pollution reduces the overall usability of water, and in some cases, such as with the presence of algal blooms, can transform entire ecosystems.
• Altering the hydrologic regimehydrologic regimeThe system that describes the occurrence, distribution, and circulation of water on the earth and between the atmosphere. through activities such as dam construction interrupts the overall functionality of water systems by slowing water flow, trapping sediments, changing temperature, and promoting the presence of non-native and invasive species³.
• Invasive species may further undermine natural communities by crowding out native species in riparianriparianReferring to the areas adjacent to rivers and streams with a differing density, diversity, and productivity of plant and animal species relative to nearby uplands. areas, changing local species composition, and affecting structural integrity as well as the ecosystem's ability to remove pollutants from the environment.
• Various land uses, such as those that require large tracts of impervious surfacesimpervious surfacesSurfaces such as paved streets, parking lots, and building rooftops that prevent precipitation from soaking into the ground. Different surfaces can have different degrees of imperviousness. (e.g., parking lots), also affect water quality and quantity. Impervious surfaces prevent rainwater from entering the soil, forcing water to flow along the land until it finds a place to drain, which impedes groundwater recharge. These surfaces also increase the quantity, speed, and temperature of water runoff and add to water pollutant loads that can reduce water quality downstream.

 Health impacts and benefits

• Clean and plentiful water resources are needed for every aspect of life. Humans require safe, potable water for drinking, food preparation, and simple everyday uses.
• Though most U.S. municipal water resources are typically treated before consumption, maintaining clean water resources helps minimize the need for and cost of this treatment. For instance, the New York City drinking water supply system is the largest unfiltered water supply in the U.S., which is made possible through strict watershed protection measures. This protected natural system has saved the state am estimated $8 - $10 billion in avoided water treatment costs⁴.
• Municipal water sources are typically treated only for those contaminants that we are aware of, thus making natural filtration by ecosystems beneficial in adding a level of protection. Contaminated water that is not adequately treated may result in waterborne disease outbreaks or serious health issues as a result of chemical or metal contaminants.
• Abundant water resources are used to grow crops, to water feed animals, and to process much of the food that we consume.
• Water resources are also used to produce power (e.g., thermoelectric, hydroelectric, nuclear) and are essential to the production of most of the material goods that people enjoy.
• Clean and abundant water resources are also needed for plant and animal survival. Wetland-dependent and aquatic species require aquatic habitats all or part of the year. These rivers, lakes, streams and wetlands are also visually pleasing and provide opportunities for people to fish, hunt, and relax.
• The regulating and filtration services provided by natural resources help maintain a clean and plentiful water supply for the entire nation.
• For more information on the health benefits of clean and plentiful water, explore the Clean Water portion of the Eco-Health Relationship Browser.

References

1. US Army Corps of Engineers. 2008. Water Supply: Value to the Nation.Exit Accessed February 2013.
2. Environmental Protection Agency. 2005. Agricultural Nonpoint Source Fact Sheet. Accessed February 2013.
3. International Rivers. Environmental Impacts of Dams.Exit Accessed February 2013.
4. New York State Department of Environmental Conservation. New York City Water Supply.Exit Accessed July 2020.