Creek-Friendly Design Considerations
Your bank stabilization project should be designed to help the stream attain a stable creek structure and incorporate features that create and sustain instream habitat. Your project should never impair, and where possible, should enhance the natural creek functions.
The following check list specifies the information we typically need to evaluate a project that contains work in and around streams. The permit applicant who uses this check list will increase the likelihood of a speedy permit review and approval, because the staff reviewing the permit will have the information they need to make an intelligent decision on the potential impacts and benefits of a project proposal.
- Describe how the project will help the stream attain an equilibrium condition so that the channel will erode and transport sediment and create and sustain instream habitat without creating conditions leading to excessive erosion and/or excessive deposition. In the process of addressing this issue of equilibrium, explain what factors are influencing the channel you are working with, such as:
- a. Is the bed materials composed of fine sediments, gravel, cobble, or bedrock?
- b. Is the stream influenced by landscape features such as alluvial fans or tides?
- c. What are the channel slopes and valley slopes, and what is the condition of the streamside riparian vegetation?
- Stream channel classification systems can be used to aid your descriptions of the conditions and channel types.
- Describe the dimensions of the stream's active channel or bankfull channel that you plan to protect or restore to achieve a balanced sediment transport and storage.
- Describe how these dimensions are derived. Provide information on the drainage area of the watershed being drained to your project site.
- Describe how the project protects and/or restores the floodplain.
- Describe how the project protects and/or restores the native streamside vegetation.
- Describe how the project protects or restores the stream channel slope by avoiding destabilizing grade control structures and/or by addressing an equilibrium channel length. Provide information on the valley slope and the proposed channel slope and sinuosity of the stream.
- For projects that entail the restoration of stream banks, provide information on the shear stresses expected to act on the banks and what soil bioengineering systems are proposed to address the stabilization needs.
- Are salmonids present in the stream where your project is located or could salmonids reach this area if migration barriers were to be removed? If so describe how the proposed project will avoid or remove migration barriers and protect or enhance spawning or rearing habitat.
For many of the smaller scale projects it may only take two pages of information to adequately describe this information. Large scale projects will require more analysis to cover these points. Owners of small parcels, as well as large project proponents may need to seek assistance from trained professionals to help address these informational needs.