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Title: Compensatory mitigation for streams under the Clean Water Act: reassessing science and redirecting policy

item DOYLE, MARTIN - University Of North Carolina
item Shields Jr, Fletcher

Submitted to: Journal of the American Water Resources Association
Publication Type: Review Article
Publication Acceptance Date: 9/14/2011
Publication Date: 2/6/2012
Citation: Doyle, M.W., Shields Jr., F.D. 2012. Compensatory mitigation for streams under the Clean Water Act: Reassessing science and redirecting policy. Journal of the American Water Resources Association. 1-16. DOI:10.111/j.1752-1688.2011.00631.x

Interpretive Summary: Many of the nation’s stream ecosystems are badly degraded, and billions of dollars are spent annually to restore or rehabilitate these systems as required by the Clean Water Act. However, published research suggests that many of these projects are inefficient or ineffective. Literature providing data on the effect of restoration projects on specific stream ecosystem functions such as flood attenuation, water quality protection, and sustenance of biological populations of concern was reviewed and synthesized. It was found that most stream restoration projects focus on relatively short reaches of channel while watershed land use controls ambient water quality and hydrology which control other functional attributes. Specific recommendations for modifications of existing policy on compensatory stream mitigation are provided.

Technical Abstract: Considerable public funds are annually expended on stream restoration projects, but available science suggests that stream restoration as currently practiced is not effective in recovering ecosystem functional integrity. The physical scale of most stream restoration projects is insufficient because watershed land use controls ambient water quality and hydrology, and land use surrounding many restoration projects at the time of their construction, or in the future, do not provide sufficient conditions for functional integrity recovery. Reach scale channel restoration or modification has limited benefits within the broader landscape context. Physical habitat variables are often the basis for indicating success, but are now increasingly seen as poor surrogates for actual biological function; the assumption ‘if you build it they will come’ is proving to be flawed and lacks support of empirical studies. If stream restoration is to play a continued role in compensatory mitigation under the U.S. Clean Water Act, then significant policy changes are needed. When used for compensatory mitigation, stream restoration should be held to some standards for actual and measurable physical, chemical, or biological functional improvement. To achieve this, greater flexibility may be required for the location of restoration projects, the size of projects, and the restoration process itself.