Environmental Management

, Volume 48, Issue 4, pp 847–864 | Cite as

Restoring Ecological Integrity in Highly Regulated Rivers: The Role of Baseline Data and Analytical References

  • Peter W. DownsEmail author
  • Maia S. Singer
  • Bruce K. Orr
  • Zooey E. Diggory
  • Tamara C. Church


The goal of restoring ecological integrity in rivers is frequently accompanied by an assumption that a comparative reference reach can be identified to represent minimally impaired conditions. However, in many regulated rivers, no credible historical, morphological or process-based reference reach exists. Resilient restoration designs should instead be framed around naturalization, using multiple analytical references derived from empirically-calibrated field- and model-based techniques to develop an integrated ecological reference condition. This requires baseline data which are rarely collected despite increasing evidence for systematic deficiencies in restoration practice. We illustrate the utility of baseline data collection in restoration planning for the highly fragmented and regulated lower Merced River, California, USA. The restoration design was developed using various baseline data surveys, monitoring, and modeling within an adaptive management framework. Baseline data assisted in transforming conceptual models of ecosystem function into specific restoration challenges, defining analytical references of the expected relationships among ecological parameters required for restoration, and specifying performance criteria for post-project monitoring and evaluation. In this way the study is an example of process-based morphological restoration designed to prompt recovery of ecosystem processes and resilience. For the Merced River, we illustrate that project-specific baseline data collection is a necessary precursor in developing performance-based restoration designs and addressing scale-related uncertainties, such as whether periodic gravel augmentation will sustain bed recovery and whether piecemeal efforts will improve ecological integrity. Given the numerous impediments to full, historical, restoration in many river systems, it seems apparent that projects of naturalization are a critical step in reducing the deleterious impacts of fragmented rivers worldwide.


River restoration Naturalization Fragmentation Baseline data Analytical references Downscaling Chinook salmon Merced California 



This research was funded by CALFED Ecosystem Restoration Program Grant ERP-02-P12-D, and was undertaken in cooperation with the California Department of Fish and Game, especially Bill Loudermilk, Patricia Brantley, and Tim Heyne. The authors are solely responsible for the views expressed in this paper, but numerous individuals contributed their skills, expertise and field labor to the project. In particular we thank Scott Dusterhoff, Yantao Cui, Noah Hume, Cliff Riebe, AJ Keith, George Strnad, Seth Gentzler, Susie Loadholt, Josh Weinstein, Kris Nehmer, Chris Neudeck, Darrell Slotten, Shaun Ayers, Nicolas Bloom, Julian Wood, Tom King, and David Bean. We also thank those who have peer reviewed various technical reports from this project, including Kris Vyverberg, Scott McBain, Jen Vick, Bill Trush, Johnnie Moore, Bill Dietrich, and Matt Kondolf. We are grateful for feedback received from the Merced River Stakeholders group, and for cooperation, insight, and data assistance from the Merced Irrigation District, particularly Ted Selb. This manuscript was improved considerably by the comments of three anonymous referees.


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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Peter W. Downs
    • 1
    Email author
  • Maia S. Singer
    • 2
  • Bruce K. Orr
    • 2
  • Zooey E. Diggory
    • 2
  • Tamara C. Church
    • 3
  1. 1.Department of Geography, Earth & Environmental SciencesUniversity of PlymouthPlymouthUK
  2. 2.Stillwater SciencesBerkeleyUSA
  3. 3.Department of Landscape Architecture and Environmental PlanningUniversity of CaliforniaBerkeleyUSA

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