Camassia Newsletter, March 1994
Study Looks at Restoring Lower Amazon Creek Wetland
The U.S. Army Corps of Engineers is studying the possibility of restoring a section of Amazon Creek to its historic flood plain and surrounding wetland.
The purpose of the Amazon Creek restoration study is to restore environmental resources, including fish and wildlife habitat lost as a result of flood-control projects, while continuing to provide flood-control benefits.
The Amazon Creek study area ( XXX see map, page 3) includes the lower Amazon Creek from Danebo Avenue downstream to Green Hill Road, as well as the section of the "A" Channel from the diversion structure to Green Hill Road and the section of the "A3" Channel from Danebo Avenue to the "A" Channel. This area was chosen because it offers the highest wetland restoration potential.
The study looks at several options:
- Remove sections of the existing channel levee along the Amazon and "A" and "A3" channels, retain a low-flow channel to direct dry-season flows, widen the channel, and reduce bank slopes as shown in the cross section to the left. Wetland vegetation would be established in the channel bottom, while maintenance and clearing requirements would be reduced. These changes would allow wetlands adjacent to the channel to flood periodically.
- Modify the levees. Under this alternative, the existing levees would either be breached with culverts or notched" by removing a small section to allow additional water into wetland areas. This option is less expensive than levee removal and allows easy control of water to adjacent wetlands. However, this option would not allow the area to return to a natural appearing and functioning condition.
- Restore and enhance the existing wetland system. This could be done by restoring a complex system of braided stream and swale features, re-establishing the mound and swale topography naturally associated with lower Amazon Creek basin, developing shallow ponds, and planting native wetland vegetation with an emphasis on establishing habitat for rare and threatened plant species.
- Build water quality retention ponds. Two retention ponds are being considered as a part of the overall landscape design. The ponds would pretreat water flows before release into natural wetland areas.
- Include the Amazon Creek bicycle path in the overall design of the project as appropriate. The bike path would follow along the north side of Amazon Creek from west Eugene to Fern Ridge Lake.
An interagency advisory committee has reviewed the draft study, and the Corps has published its findings and recommendations in a report titled Amazon Creek: Environmental Restoration and Reconnaissance Study.
In the next phase, the Army Corps of Engineers and the City of Eugene will consider the feasibility of proceeding with various options.
A Delicate BalanceThe Amazon Creek wetland restoration study is an effort by the U.S. Army Corps of Engineers to integrate multiple objectives into its planning process. In the early 1940s, the Corps built Fern Ridge Reservoir in response to flooding problems in the Willamette Valley. In 1959, the Corps completed a flood control project along Amazon Creek consisting of approximately eight miles of concrete and earthen channels and a 3.8-mile-long diversion canal emptying into Fern Ridge Reservoir. The channelization of the Amazon Creek system has attected the natural environment. Designed to provide flood control, these projects reduced the water supply to natural wetlands, diminished the regular flooding that provided water and nutrients to the wetlands, and drained adjacent wetland areas. Furthermore, increased flood security allowed for a more intensive level of agricultural and industrial development to occur in the area. The net result has been the loss ot signiticant wetlands and ash forest that provided habitat for many endangered and threatened plant species. |
