A watershed is an area of land in which all surface and groundwater flows downhill to a common point, such as a river, stream, pond, lake, wetland or estuary. An estuary is a partly enclosed coastal body of water in which river water is mixed with seawater. Despite the differences in size, all watersheds share common properties. They all perform the same function of transporting water over the earth's surface. We all live in a watershed. If your feet are on the ground, you're in a watershed.
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Water seeps down through the soil to aquifers, which are underground rivers that slowly move water below the watersheds to outlet points at springs, rivers, lakes and oceans.
Construction projects like dams can limit the flow of water; construction of roads and buildings can divert and even increase the flow of water. Agricultural fertilizer can run off of crop fields and inadvertently harm microorganisms in rivers and lakes, having an adverse effect on water quality and marine life. The irresponsible disposal of household and industrial chemicals can be harmful because these chemicals travel through the watershed, poisoning life and damaging the ecosystem.
Many communities use rivers and streams as their source of drinking water. Water treatment prepares this water for human consumption, but if the water is laden with chemicals and microorganisms, it can be difficult to treat effectively.
Homes built on flood plains, low-lying areas adjacent to rivers, are susceptible to flooding conditions when heavy precipitation exceeds the watershed's capacity to absorb water. Rivers, streams, and lakes overflow, threatening human lives, and damaging or destroying roads, buildings, and flood control measures.
When a watershed becomes dry due to a lack of precipitation, this can cause a water shortage for those who depend on their lakes and rivers for drinking water.
Stormwater is any precipitation that falls from the sky including rain, hail, and snow. In a natural landscape without development, stormwater is absorbed into the ground or falls into bodies of water. This gives needed water to plants and animals, and it replenishes reserves of surface and groundwater.
In developed urban areas, stormwater falls onto impervious surfaces (surfaces that do not absorb water) such as roads, sidewalks, rooftops, or parking lots and is not soaked up by the ground. As a result, the falling water is swept across the surface as runoff; finding its way into a local waterway or it is directed into a local waterway through a storm drainage system.
Stormwater can pick up debris, chemicals, dirt, and other pollutants and flow into a storm drainage system or directly to a local waterway. Anything that enters the storm drainage system flows directly into the waterbodies we use for swimming, fishing, and providing drinking water.