What is a Watershed?

Watersheds are nature's boundaries for water resources. A watershed encompasses all areas that drain to a common waterbody such as a lake, river, or estuary. When rain falls or snow melts, water either flows downhill, eventually reaching the ocean, or percolates through the soil and replenishes groundwater. As it flows, water picks up pollutants, including sediment and debris. As a result, physical, chemical, biological processes, and human activities within a watershed affect water, land and other natural resources.

Evolution of Watershed Management

Since passage of the Clean Water Act about 30 years ago, regions throughout the country have made significant progress in protecting and restoring the health of the nation’s waters. Much of this progress is a result of tighter controls on pollution from industry and sewage treatment plants.

Despite these efforts, 40 percent of our nation’s waterways are still unsafe for fishing and swimming. While pollution from factories and sewage treatment plants, soil erosion, and wetland losses have been dramatically reduced, runoff from city streets, rural and agricultural areas, and other sources, commonly referred to as non-point sources, continues to degrade the environment and puts drinking water supplies, aquatic habitats and other water uses at risk.

Today's problems call for more creative, comprehensive solutions. In recent years, the U.S. Environmental Protection Agency (EPA) has joined with other public and private entities to promote community-based watershed management programs as a means to further restore and maintain water quality, protect sensitive habitats, and preserve land resources. In particular, the EPA has been working with federal, state, and local governments to customize activities and services for local watersheds and affected groups.

The Watershed Management Approach

A watershed management plan is one strategy for effectively protecting and restoring aquatic ecosystems, protecting human health, and preserving other natural resources. This strategy is based on the premise that many water quality, ecosystem, and land resource problems are best dealt with at the watershed level rather than at the individual waterbody (e.g., river segment) level. Major features of a watershed management plan are identifying and assessing priority problems, encouraging a high level of stakeholder/local resident involvement, and measuring program success through monitoring and other data gathering.

Ventura County Watershed Zones

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