Lance Olsen
Dam Removal
Introduction: Dams are in all ecosystem types where flowing water is present
Dams Beginnings
Mesopotamia (3000 B.C.)
Tigris and Euphrates
Ancient Dams still in existence?
India and China
Types of Dams
Arch, Gravity, Arch-Gravity, Barrages, Embankment, and Beaver
Number of Dams (Ohio and Worldwide)
Worldwide (48,000 dams over 15m high)
Ohio (50,000 classified, most are small and do not fall under Ohio’s Dam Safety Laws, 2700 are of
lawful concern to Ohio)
Positive Impacts of Dams
Provide 19% of the world’s power
In a larger sense this is impacting the human component of the ecosystem
Create recreation for fishermen, boaters, families..etc.
Produce new habitat for other species that have evolved to be more lentic
Increase total local economic surplus by creating additional jobs and businesses
Provide drinking water, agricultural irrigation, and sewage storage (not simultaneously)
Flood Control
Negative Impacts
Change stream mophometry
Impact river communities
Block Migration of species, create an impassable boundary
Act as a vector to disease
Alter flow regimes and timing
Decrease sediment load
Disrupt chemical processes
Catastrophic failure
http://www.youtube.com/watch?v=65D_E5SQqbo&feature=related
Change river temperature
Process of Dam Removal
-Pre-removal
Contact local, state, and federal agencies
Gather funding
Retain the proper permits
Involve all project stakeholders (Landowners, Dam owner, local officials)
Hold meetings, send mailings…etc.
Determine past, present, and future impacts of the dam vs. removal
(Take core samples upstream to determine depth of the streambed materials, review
samples behind the dam to determine if sediment is to be removed…etc.)
Establish costs both monetary and environmental
-Removal
Contractors with large equipment
Staged removal
Problems during removal
-Post Removal
Physical
Altered Flow
Erosion
Increased sediment transport
Decreased water temperature
Channel Formation
Progressive Downcutting
Chemical
Mobilization of phosphorus
Mobilization of organic contaminants
Improved water quality
Biological
Increased fish diversity and habitat quality
Restoration of fish passage
Change in community composition from lentic to lotic
(Fish, Micro/Macro Inverts…etc)
Plant Colonization
Recent Publication
- “Benthic invertebrate assemblage change following dam removal in a Wisconsin stream” by Amina
I. Pollard & Reed T., Hydrobiologia (2004).
- Sampled Three sites before and after removal: upstream, dam, and downstream to identify changes
in the feeding groups and invertebrate composition.
(How did invertebrate assemblages differ along Turtle Creek before dam removal? How did the
assemblages change one year following the removal? What are the possible changes that explain
invertebrate distribution?)
- They found similar invertebrate communities upstream and downstream prior to removal with the
dam being unique from the others. Both upstream and downstream sites were dominated by a single
functional feeding group and had low evenness. The dam site had a diverse functional feeding
composition and high evenness. After removal assemblages were similar at all three sites without
many changes. However, functional feeding composition was different at the upstream site after
removal. Results also suggest that a relationship exists between local conditions and community
structure.
References
Hart, D.D, et al. 2002. Dam Removal: Challenges and Opportunities for Ecological Research and River
Restoration. Bioscience, Vol. 52. Pgs. 669-681.
Snodgrass, J.W., & G.K. Meffe. 1998. Influence of Beavers on Stream Fish Assemblages: Effects of Pond
Age and Watershed Position. Ecology, Vol 79(3). Pgs. 928-942.
Lessard, J.L., & D.B. Hayes. 2003. Effects of Elevated Water Temperature on Fish and Macroinvertebrate
Communities Below Small Dams. River Res. Applic. Vol 19. Pgs. 721-732
Evans, J.E., et Al. 2000. Lessons from a Dam Failure. Ohio Journal of Science, Vol., 100(5). Pgs. 121-131.
Pizzuto, J. 2002. Effects of Dam Removal on river Form and Process. Bioscience, Vol. 52(8). Pgs. 683-691.
Pollard, A.I., & T. Reed. 2004. Benthic invertebrate assemblage change following dam removal in a
Wisconsin Stream. Hydrobiologia, Vol. 513. Pgs. 51-58