Environmental Management

, Volume 27, Issue 6, pp 803–814

Undamming Rivers: A Review of the Ecological Impacts of Dam Removal

  • ANGELA T. BEDNAREK

DOI: 10.1007/s002670010189

Cite this article as:
BEDNAREK, A. Environmental Management (2001) 27: 803. doi:10.1007/s002670010189

Abstract

Dam removal continues to garner attention as a potential river restoration tool. The increasing possibility of dam removal through the FERC relicensing process, as well as through federal and state agency actions, makes a critical examination of the ecological benefits and costs essential. This paper reviews the possible ecological impacts of dam removal using various case studies.

Restoration of an unregulated flow regime has resulted in increased biotic diversity through the enhancement of preferred spawning grounds or other habitat. By returning riverine conditions and sediment transport to formerly impounded areas, riffle/pool sequences, gravel, and cobble have reappeared, along with increases in biotic diversity. Fish passage has been another benefit of dam removal. However, the disappearance of the reservoir may also affect certain publicly desirable fisheries.

Short-term ecological impacts of dam removal include an increased sediment load that may cause suffocation and abrasion to various biota and habitats. However, several recorded dam removals have suggested that the increased sediment load caused by removal should be a short-term effect. Preremoval studies for contaminated sediment may be effective at controlling toxic release problems.

Although monitoring and dam removal studies are limited, a continued examination of the possible ecological impacts is important for quantifying the resistance and resilience of aquatic ecosystems. Dam removal, although controversial, is an important alternative for river restoration.

KEY WORDS: Dam removal; Restoration; Mitigation; Flow regime; Sediment; Fish passage

Copyright information

© Springer-Verlag New York Inc. 2001

Authors and Affiliations

  • ANGELA T. BEDNAREK
    • 1
  1. 1.Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6018, USA, The Patrick Center for Environmental Research, The Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, Pennsylvania 19103, USAUS