Watersheds and their hydrological features provide key functions to natural ecosytsems. Destorying or altering these features in any way can have a huge impact upon the natural environment. A watershed is defined as an area of land where all of the water that falls upon it, is under it, or drains off of it, converges into specific lakes, rivers, streams, wetlands, or oceans.

Watersheds are bounded by topographical high points known as divides, such as ridges, hills, or mountaintops. Watersheds come in different shapes and sizes, with the larger ones such as the Willamette River Basin being divided into smaller subbasins. Our actions on the land directly affect the water quality and quantity for all communities living downstream.

Willamette River Watershed

Marion County lies within the Willamette River Watershed (Basin) which is Oregon’s largest watershed at 11,500 square miles. Roughly 70 percent of the state’s population currently lives within this watershed. The valley’s population is expected to nearly double by 2050 making it the fastest growing region in Oregon. This makes protecting the watershed an important goal for Oregon and the future of the region. The Willamette Valley is characterized by mild wet winters and warm dry summers, with fertile soils that make the valley the most important agricultural producing region in Oregon. As the pressures of development increase, conflict between the natural environment and urbanization will also increase. With approximately 96 percent of the valley floor (Willamette Ecoregion) in private ownership, conservation efforts and watershed protection relies on voluntary actions by property owners.

Development has already greatly altered the valley from its historic environment of grasslands, oak savannas, wet prairies and other open habitats. The Willamette River has been disconnected from its natural floodplain and much of the historic wildlife habitat is fragmented.


Wetlands and their adjacent ecological transition zones are important features of a watershed. The flow of water, the cycling of nutrients, and the energy of the sun meet to produce a unique ecosystem characterized by its hydrology, soils, and vegetation. Wetlands can be classified into four general categories: marshes, swamps, bogs, and fens. Wetlands have two primary characteristics: hydric (water logged) soils and water tolerant plants. Even when water isn’t visible these indicators will still be present.

Wetlands are home to thousands of species and provide important breeding areas. Wetlands’ natural systems are critical to maintaining the ecological balance of a region. They help reduce flooding by storing water, and help reduce water pollution through their filtering and cleansing abilities.

Riparian Areas

Riparian areas are defined by the Natural Resources Conservation Service as ecosystems that occur along waterways and water bodies. They act as the transition between the wet (aquatic) lands and the dry (terrestrial) land. A healthy riparian area will be highly vegetated with ideal riparian vegetation, good shade, and an abundance of woody and organic debris. Plant roots provide the bank with increased stability while minimizing sediment runoff. Riparian buffers should be between 25-100 feet wide depending on surrounding land uses. Properly managed riparian areas provide property owners and the environment with numerous benefits. Riparian areas are vital to the natural ecosystem, thus property owners are highly discouraged from altering or removing riparian vegetation.