Stream Rehabilitation Project - Bio-engineering

In 1996, the RBWRP used bio-engineered techniques to restore natural channel design characteristics, bank stability and riparian vegetation to a section of the John Clark Drain which had been degraded by previous drainage works and cattle access to the watercourse. The 3.6 hectare (9 acre) site is a cattle pasture which is unevenly divided by the stream that passes through it.


Eroding areas of the stream banks were re-graded to a 3:1 slope. A single layer of willow fachines was entrenched at the base of most eroding areas with a Red-osier Dogwood brushlayer up-slope. A Flexblock(r) armoured stabilization mattress system (concrete blocks locked together with flexible, non-corrosive connecting cables) was placed at the base of the remaining two slopes which were expected to continue to experience elevated erosive action. Live stakes were then pounded into the ground in the gaps between the cement blocks. All exposed soil was seeded with a mixture of Oats, Canada Wild Rye, Creeping Red Fescue and Annual Rye Grass. The re-graded stream banks were then covered with coir matting erosion control material secured in place with live willow stakes.

The stream at the top and bottom ends of the pasture already had a relatively well-developed flood plain. In the centre of the pasture where the stream had become entrenched, the stream was widened by approximately 1 m. Brush mattressing was then used to develop a low flow channel through the area. Vortex weirs were placed in-stream at the lower end of the pasture to assist in maintaining the drop and pool formation already present in the stream in this location. Soil removed from the banks was used to create a small berm to reduce water flow over the stream banks while a major gully eroding the bank of the stream at the bottom of the pasture was filled and the water re-routed via a grassed waterway to the adjacent road drainage ditch.

High school students and environmental clubs participated in the project, gaining hands-on experience of how effective agricultural drainage can be achieved while maintaining the health of the natural habitat and fish and wildlife communities associated with our streams. Students cut the live, dormant shrub material that had been collected into fachines and live stakes, placed fachines in the trenches that they had dug, cut and placed coir matting along re-graded stream banks and pounded live stakes into the ground. The smaller portion of the pasture has been permanently retired from grazing and the larger portion, to remain in use, will be fenced to prevent future cattle access to the watercourse.

The remedial actions taken will protect the land, minimize soil erosion and alleviate stream pollution (sediment, bacterial, nitrogen) and fish habitat degradation resulting from direct cattle access to the stream. The roots and shoots that develop from the Willow and Dogwood cuttings in the spring will stabilize the stream banks by reinforcing the soil with roots. Growth of the shrubs will provide a riparian corridor that will be an important source of food and shelter for a variety of wildlife species. Re-vegetation of the stream banks will shade the stream reducing water temperatures and, together with increased water quality, will produce an environment more suitable for invertebrate production. Fish habitat remediation will be attained through increased food availability and increased shelter provided by the re-vegetated stream edges. Six nesting boxes from the RBWRP's Eastern Bluebird Project were placed in the pasture and are being monitored by a volunteer. Water quality monitoring will provide quantitative measurements of the improvements achieved.

This natural channel design / bio-engineering project was the first of its kind in the area. It provides an important example of remediation of rural, non-point source pollution and promises to be very important in shaping future drainage works in this region. The RBWRP intends to focus attention on this project as a demonstration of ecologically-sound drainage works and will support the incorporation of these methods into future drain construction and re-construction works in the area.

Partners:

Back to Accomplishments...

Back to the Rondeau Bay Watershed Rehabilitation Program

More Information on Stream and Riparian Habitat Restoration