Virtually all watersheds have been modified or degraded by development, often resulting in the deterioration of water quality, damage to plant and animal communities, erosion, and other wounds. This reduction in the quality of ecosystem services may have significant economic and social implications as well.
A watershed may be defined as the collection land surfaces draining to the same body of water. Smaller watersheds combine to form larger watersheds. The Columbia River watershed is composed of thousands of small stream-scale watersheds, ultimately draining parts of Oregon, Washington, Idaho, Montana, Wyoming, Nevada, Utah, and British Columbia.
Watersheds are functional units of ecosystems, and best treated as whole systems. They provide a wide range of watershed services, including air and water purification, flood control, habitat, and recreation. Degraded watersheds may show numerous symptoms, including erosion, loss of plant and animal species, decreased ability to hold water during storms (leading to more frequent and sever flooding), and habitat fragmentation.
Watershed restoration is the process of restoring fully functional ecosystems at the watershed scale. This requires that the full complement of native plants and animals be reintroduced, perhaps over several decades. It is particularly important that large carnivores and "keystone" species, which each play a role in regulating food webs far out proportion to their numbers, be restored. Revegetation, particularly in riparian zones, can renew soil fertility and reduce erosion. Natural disturbances, including floods and fire may need to be re-established or effectively mimicked. Obstacles to species movement need to be addressed, thereby reconnecting isolated habitats.
Watershed restoration brings particularly significant economic benefits in an urban setting, where it enhances ecosystem services and directly impacts thousands of people. In rural areas, major economic uses of the land, including forestry, agriculture, and fisheries can directly contribute to watershed restoration as they shift towards sustainable forestry, agriculture, and fisheries. Restoration in a wildlands setting can establish and enhance wildlife corridors, improve the health of buffer zones, and play a role in establishing core reserves in disturbed areas. On a small scale, yards, gardens, landscaped grounds, and parks can all be planted with native species.
In the Pacific Northwest, restoration of watershed services is a major economic sector, with hundreds of millions of dollars allocated to salmon, wetlands, forest, and grasslands restoration. It remains an imprecise science, but holds enormous promise to eventually return the nature of the bioregion to ancient levels.
Treat watersheds as whole systems, seeking to restore a full complement of native plants and animals, re-establish natural disturbances, stabilize soil, and connect habitat with surrounding watersheds.
Examples of this pattern in action:
Watershed Research and Training Center
"The primary objectives and purposes of this corporation shall be the promotion of the sustainability of a healthy community economy in healthy forests through research, training, education and economic development." The By Laws
Johnson Creek Watershed Council
Organizations whose work incorporate this pattern:
American Fisheries Society, . Watershed Restoration: Principles and Practices. American Fisheries Society. Bethesda, MD. 1997.
Rapp, Valerie. What the River Reveals: Understanding and Restoring Healthy Watersheds. The Mountaineers. Seattle, WA. 1997.
Riley, Ann L. Restoring Streams in Cities: A Guide for Planners, Policymakers, and Citizens. Island Press. Washington, DC. 1998.