Restoring rivers

Talk about it

Moving water has a fascinating vitality. Like watching fire, flowing water is mesmerizing. The fluid dynamics are constantly changing patterns of turbulence and color and light. We have spiritual attachment to rivers; as well we should because they are life-giving.

We also have a compulsion to modify them. Like kids in a puddle, people seem to have to mess with rivers. We have dredged, dammed, diverted, channelized, and polluted most rivers on the planet.

Wholesale conversion of landscapes for agriculture and urban development have altered the hydrology of many rivers, reducing infiltration into the ground and the time that it takes for rainfall and snowmelt to reach the rivers, resulting in more “flashy” flow with higher flood peaks and smaller low flows.

In our region, clearing of forest, plowing the prairies and the agricultural practices in the late 1800s and early 1900s resulted in tremendous volumes of soil erosion. Most of the topsoil from upland areas and sediment eroded from gullies ended up in valley bottoms. Many small mill dams built on rivers in our area filled with sediment and then washed away. Today, many rivers in our region have channels that are incised through many feet of historically-deposited sediment.

Since the 1930s, there have been many efforts nation-wide to restore rivers. Billions of dollars have been spent on river restoration. In Wisconsin, as of 2006 according to the National River Restoration Science Synthesis Report, over 400 river restoration projects have been completed at a cost of over $86 million. Most are in-stream habitat modifications or dam removal projects.

In Wisconsin, non-governmental conservation organizations like Trout Unlimited, local sportsmens’ clubs and the River Alliance of Wisconsin work closely with the Department of Natural Resources in conducting river restoration projects. Around here, habitat improvement projects have been constructed on the Willow, Kinnickinnic and Rush rivers, the South Fork, Isabelle Creek, Lost Creek, and Plum Creek. Trout Unlimited members are currently working with the DNR on a habitat project on Pine Creek near Maiden Rock.

Rivers are conveyors of water and sediment. Flowing water mobilizes sediment and transports it downstream and onto its floodplain during high flows. The water conveys sediment as bed load which bounces along the bottom, and as suspended load. Rivers form their channels and floodplains.

Depending on the geology of the watershed, the availability of sediment, the slope and flow regime, the river channel form is dynamic and characteristic of the setting in the landscape and drainage network.

River restoration requires understanding of fluvial geomorphology — the processes of river flow and sediment transport and deposition. River restoration also requires an understanding of the pre-development condition of the river and its history of alteration leading to its present condition.

On many cold-water rivers in our area, projects have been built to improve habitat for native brook trout and the non-native brown trout. Most have involved making the streams narrower and deeper, with exposed gravel in the bed for spawning habitat and cover for fish.

On the Rush River in Martell, the reach above the lower bridge was wide and shallow with little habitat for trout. The habitat project installed there a couple years ago included a sinuous, narrow, rock-lined channel with a wider bench on the sides to convey flood flows. Trout are definitely using that modified reach of river. They are easy to spot from the bridge.

Although the modified reach of the Rush River at Martell is not true river restoration (the Rush River was not configured like that prior to development), it does provide improved habitat for trout and good sport fishing opportunity.

Many river restoration projects have imposed single-thread meandering channels on streams that don’t build their own channels in that form. There is a deeply rooted cultural preference for such meandering channels that has its roots in 18th century landscape theory. In his 1753 book, Analysis of Beauty, the English artist William Hogarth noted the importance of serpentine line in our appreciation of beauty in nature.

“The eye hath this sort of enjoyment in winding walks, and serpentine rivers, and all sorts of objects, whose forms, as we shall see hereafter, are composed principally of what I call waving and serpentine lines ... that leads the eye in a wanton kind of chase, and from the pleasure that gives the mind, entitles it to the name of beautiful.”

Protecting and restoring rivers is a worthwhile effort that produced real benefits to society. The noted fluvial geomorphologist Luna Leopold (Aldo Leopold’s son) said, “Water is the most critical resource issue of our lifetime and our children’s lifetime. The health of our waters is the principal measure of how we live on the land.”

Please send any comments and suggestions for this column to me at wildside@rivertowns.net.

Tags: outdoors, streams, and, rivers, walks, fishing, water, dan, wilcox