Background Information

What is a Watershed?

A watershed is a land area from which water drains into a receiving body of water. Receiving bodies of water can include streams, lakes, wetlands, estuaries, and groundwater. Watersheds come in different shapes and sizes, and local watersheds are subwatersheds (or subbasins) of larger, regional ones. The Potomac watershed, for example, is a subbasin of the larger Chesapeake Bay watershed.

What is Nonpoint Source Pollution?

Unlike pollution from factories and sewage treatment plants, nonpoint source pollution comes from many different areas with no particular place of origin. It is caused by rainfall or snowmelt moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters, and even underground sources of drinking water. These pollutants include:

Excess fertilizers, herbicides, and insecticides from farms, cities, and suburban streets
Oil, grease, and toxic chemicals from urban runoff and energy production
Sediment from improperly managed construction sites, crop and forest lands, and eroding streambanks
Salt from irrigation practices and acid drainage from abandoned mines
Bacteria and nutrients from livestock, pet wastes, and faulty septic systems

Acid rain and changes to stream flow, such as dams and concrete channels, are also sources of nonpoint source pollution. Acid rain, much of which comes from cars and power plants, is rich in nitrogen, which can overstimulate the growth of aquatic weeds and algae. This in turn can deplete oxygen and kill aquatic life. Channelization reduces the ability of streams to assimilate or absorb waste and disturbs fish breeding areas.

What is a Wetland?

Wetlands are areas of land that are wet at least part of the year. Wetlands are populated by plants well adapted to grow in standing water or saturated soils. There are many different types of wetlands, including marshes, bogs, fends, swamps, prairie potholes, and bottomland hardwood forests. Wetlands may not always appear to be wet. Many dry out for extended periods of time. Others may appear dry on the surface but are saturated underneath.

What are the Basic Characteristics of Wetlands?

Wetlands share three basic characteristics: 1) hydrology (water), 2) hydric soils (soils that form due to presence of water), and 3) hydrophytic vegetation (plants adapted to living in soils that are saturated).

Wetland Benefits

These complex ecosystems play an important role in the health of our environment and the quality of our water. Wetlands provide support for:

Fish and wildlife habitats
Complex food webs
Water absorption to reduce storm flooding and damage
Sediment traps
Erosion control
Water quality
Groundwater replenishment; maintaining flows in streams by releasing water during dry periods
Open space and aesthetic value

What is Groundwater?

Beneath the land's surface, water resides in two general zones, the saturated and the unsaturated. The unsaturated zone lies directly beneath the land surface, where air and water fill in the pore spaces between soil and rock particles. Water saturates the zone beneath the unsaturated one.

Did You Know?

Half the drinking water in the United States comes from groundwater.

The term "groundwater" refers to water in the saturated zone. This water is an important natural resource and used for many purposes, including drinking water, irrigation and livestock raising.

Half the water used in the United States for drinking water comes from groundwater.

Surface water replenishes (or recharges) groundwater when it percolates through the unsaturated zone. Therefore, the unsaturated zone plays an important role in groundwater hydrology and may act as a pathway for groundwater contamination. Groundwater can move laterally and emerge at discharge sites, such as springs on hill sides, or seep in from the bottoms of streams, lakes, wetlands, and oceans. Therefore, groundwater affects surface water quantity and quality because polluted groundwater can contaminate surface waters. Conversely, some surface waters, such as wetlands, hold flood waters and allow them to soak slowly into the groundwater. When wetlands are filled or drained, groundwater may dry up.

The Environmental Protection Agency is requiring water suppliers to put annual drinking water reports in the hands of their customers. Between April and October 1999, and by July 1, thereafter, water suppliers will be providing "Consumer Confidence Reports." These reports, to be issued with utility bills, will provide fundamental information, including, for example, the source of your local drinking water (lake, river, aquifer, or other source), its susceptibility to contamination, and the level or range of any contaminants found.

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