Riparian areas are terrestrial environments that exert influence on a stream and/or are influenced by the water body. Riparian habitats are home to a rich diversity of plant and animal life and provide nutrients and food to the aquatic environment.
Distribution of riparian habitat
The MFWW has rich and varied riparian vegetation throughout the watershed. Riparian vegetation is generally the most robust and intact in upper watershed areas, with more disturbance downstream near population centers, and areas of agricultural use. Lower reaches of the river, particularly near the confluence with the mainstem of the Willamette, include more than 1300 acres of intact wetlands and hundreds of acres of former wetlands.
Threats to riparian environments in the MFWW
Critical Riparian Habitat: Native riparian forest and backwater sloughs provided essential habitat for terrestrial species such as Western pond turtle, Oregon chub, Northern red-legged frog, migratory songbirds, bald eagles and others. Flood protection dams have reduced stream flow variability in mainstem sections of the river. This has caused a reduction in habitat forming peak flows, changing riparian vegetation composition. Large swaths of riparian forest associated with former multi-channel river patterns were greatly reduced in favor of agriculture and development, and riparian forests currently exist only in thin strips immediately adjacent to a stabilized river channel.
Invasive Plants and Loss of Native Habitat: If left unchecked, many invasive plants have the potential to transform entire ecosystems by out-competing native species and, consequently, reducing native fish and wildlife habitat. Invasive plants are prevalent throughout the watershed, particularly below Dexter Dam. Weed species that have invaded habitats, particularly riparian areas, include Armenian blackberry, Scot’s broom, Japanese knotweed and false-brome.
Council goals for riparian habitat:
- remove non-native species and enhance native species distribution
- encourage development of mature riparian forests for canopy cover and contribution of large wood
- encourage use of bioengineering for stabilizing streambanks
Projects involving riparian habitat:
- Eastgate Woodlands
- Greenwaters Riparian Enhancement
- Lost Creek Confluence Restoration Project
- Lost Creek Japanese Knotweed Removal
- Lost Creek Riparian Revegetation Project
- Small Grants Lost Creek Riparian Restoration Projects
- Nelson Creek Confluence