A Primer on Streams and Stream Restoration
Nearly Iowa's streams suffer from the same basic problem: they need to handle too much water that comes too quickly. The result has been that they have cut deeper channels and lost access to their floodplains. Closely related to this is the tendency for streams to erode sideways, making steep outside banks and murky, sediment-laden water. The reasons are several: bare soil in the watersheds, lost topsoil and its sponge effect, impermeable surfaces like roads, annual crops instead of perennial prairies, and straightening of many streams to recover potential ground.
Leeward Solutions has answers to the problems of stream stability: sideways erosion of agricultural and other land, excavating new meanders in a straightened stream, increasing the storage space for water during floods, and halting the formation of new gullies. A combination of experience from observing streams of all sizes at various stages or levels of flow and technical skills in documenting and quantifying the features and functions of a channel allow us to plan and implement successful restoration projects.
Leeward offers an initial short site visit to talk over your ideas about the issues, suggest answers, and arrange for a brief Stream Restoration Survey. The Stream Restoration Survey allows us to tell you in more detail what is happening. More importantly it is the stepping stone to a full Stream Survey, project design, permit applications, and exploration of funding sources to enhance your land. Land in Iowa can be valued in many ways, not least of which is as an economic and productive asset. We work with you to assess your values and design a project plan to meet them.
MORE ABOUT STREAM RESTORATION & STABILIZATION
Effective stream restoration and stabilization efforts are NOT the result of a one-size-fits-all approach. While there are any number of proven practices that may be used, not all are appropriate for a given site. The practices that DO work are the result of stream analyses (see Stream Visual Assessment and Stream Morphological Analysis for more information) that tailor their application to the characteristics of the site and the stream. It is essential that visual and morphological surveys are used to design baffles, new channel routes, resloped banks, revetments, and other practices.
Planning also requires application for appropriate permits, working with neighbors, and overall project designs that don't push a problem across or the down the river. If the erosion, flooding, or other problem is relocated elsewhere, the project is a failure.
The banner image above comes from the pre-design stage of work with a client along an Iowa stream. While there is a good chance that something like this image will be implemented, it is a prototype for a more thorough design that accounts for the watershed, stream corridor, land uses, and natural stream functions. lo
In general, stream restoration and stabilization should meet these minimum goals:
- avoid harm to any Endangered, Threatened, Special Concern, or rare species of animals and plants.
- result in the same or a longer channel length and width. If the length and/or width are reduced, the capacity of the stream to handle floods is reduced, and likelihood of damage from erosion is increased.
- install structures to dissipate the energy of the stream at or near key erosion points, without merely transferring the erosive energy elsewhere.
- take into account the entire watershed at and upstream from the project location, even if the repairs address problems on only one property.
- plant sloping banks with deep-rooted perennial plants and replace any vegetation that is destroyed during installation with appropriate native plants and plant mixes.
- take into account historic changes to the stream near the installation site, by using aerial imagery, landowner or resident knowledge, and other sources.
Leeward Solutions specializes in organizing the overall project, from start to finish, providing project oversight to make certain that the installation meets the design and, even more important, returns to you the best longterm outcome.
This shallow headwater gully formed in a grassy waterway below crop acres. Unless corrective action is taken, the gully will deepen and lengthen. The concrete rubble adds to the problems by forcing the water to widen the gully.
