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Erosion and Sedimentation

The Threat

The Ausable River watershed boasts forested streams with abundant scenic views and recreational opportunities, but such measures are deceptive as indicators of wild nature or stream health. Historic land clearing, industrial operations that altered stream channels, and development in the floodplains of the Ausable valley changed the physical characteristics of the river, destabilizing its ability to move sediments efficiently and manage flood flows. Modern land clearing and urbanization of the river corridor and human alterations of the channel, in the forms of bridges, rip-rap, dredging, and dams, have left the Ausable in a state of disequilibrium.

When streams are in disequilibrium, excessive erosion occurs in some locations, while excessive sediment deposition occurs at others. Sand, gravel, cobble, and boulders from collapsing banks destabilize a stream, widening and overfilling its channel, undoing its natural balance and resilience. In a healthy, balanced river, a typical spring flood would move small sediment efficiently to floodplains and sort larger materials along its bed and banks. But in a destabilized stream, the same flood scours banks, fills delicate pool habitats with sand, piles cobble in shallow riffles, and cuts off access to floodplains. The cycle repeats, banks continue to erode, trees fall, habitat is smothered, and flood resilience for our communities declines, while maintenance costs mount.

AsRA's Response

The process of re-building a healthy, free-flowing stream with diverse habitats, capable of maintaining its pattern and structure even during a flood, has many inter-related components. AsRA evaluates stream systems - considering the needs of the human communities around them - and implements projects that help streams regain their balance, improving wildlife habitat, water quality, and flood resilience. Projects fall into three broad categories: natural channel design restoration of stream channels, banks, and floodplain access; road-stream crossing retrofits or replacements that restore connectivity and habitat; and riparian restoration of near stream environments. AsRA also takes on other projects, such as the Rome Dam removal, which advance our goal of a healthy, self-regulating Ausable River.

The effectiveness of these interventions will only be as successful as our communities' willingness to give streams the room to roam - as healthy streams do over time. Only then can they find and maintain their equilibrium and manage storm flows. AsRA actively supports the development and use of cooperative agreements, regulations, and easements that protect river corridors, wetlands, meander areas, and floodplains from development, that limit new encroachments (e.g. roads, bridges, berms) on streams, and - where possible - reduce existing encroachments.

What You Can Do

If you own streamside property and have an established riparian buffer, do not cut it down. Large trees, though they may block your view of the river, serve as anchors for a healthy streambank or shoreline. If you lack streamside cover, plant dense native buffers along streams and ephemeral waterways.

If you have severely eroded banks or decaying unused structures in or on a stream or streambank, contact AsRA for assistance in assessing them.

AsRA is working hard to protect the Ausable River.
Read the latest stories about the Ausable River.
Explore the wonderful recreational resources of the Ausable.
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