Dams and Impounded Rivers - River Dynamics and Integrated River Management - page 432

an effort to restore habitat. It is a cautious, risk-averse approach to dam decommissioning and will do
much to repair one of Georgia Strait's great salmon rivers.” (http://www.irn.org/revival/decom/brochure/
rrpt2.html, 2007).
Czech Republic —Since 1991, local NGOs and concerned citizens have campaigned to remove three
small dams that flooded 1,300 acres of riparian and woodlands habitat along the Morava and Dyje rivers.
The Ramsar Convention, which lists the affected area as a wetland of international importance, obliges the
Czech Government to maintain the ecological character of the site. While conservation groups succeeded
in securing a degree of restoration through partial draining of two reservoirs in 1995, the Czech Ministry
of Agriculture may not support the ongoing restoration efforts. Czech conservation groups such as the
Ecological Institute Veronica continue to demand decommissioning of the Nove Mlyny dams and further
restoration efforts in the area.
Thailand —In Thailand, decommissioning campaigns have arisen as a result of social and ecological
disruptions caused by dam construction on the Mun River, the largest tributary of the Mekong. The 135 MW
Pak Mun Dam was funded by the World Bank and completed in 1994. As a direct result of the dam, more
than 20,000 people have been affected by drastic reductions in fish populations upstream of the dam site,
and other changes to their livelihoods. Villagers occupied the dam site and are demanded that dam gates
be permanently opened to allow fish migration. The Rasi Salai Dam, the first project to be completed in a
massive scheme to build 13 irrigation dams on the Chi and Mun rivers, is currently useless and likely to
remain so. The reservoir overlays a geological salt dome that now makes the water too salty for irrigation.
It also inundates the largest freshwater swamp forest in the Mun River basin, a source of food and
traditional medicine for local villagers. More than 15,000 people lost farmland due to the reservoir, 60%
of whom remain uncompensated.
7.3.2.3 Ecological Restoration After Dam Removal
In many cases dam removal is effective for ecology restoration. For instance, one year after the Edwards
Dam removal in 1999, migratory fish returned in abundance to previously impounded parts of the
Kennebec River. Fish diversity in the Baraboo River more than doubled, from 11 to 24 species, just 18
months after restoration of free-flowing conditions. Two years after removal of a dam on Tea Creek, the
number of trout soared to more than 6 times the population necessary to reach “Class A” (the highest
rating for recreational fisheries)
The state of Wisonsin leads the U.S. in dam removal. Over 130 dams have been removed in Wisconsin
which is why Wisconsin has earned the reputation as a leader in selective dam removal internationally.
Three major reasons for dam removals are: (1) removal of unsafe structure under chapter 31.19 of the
state statutes; (2) removal of abandoned dams when either no owner is found or the owner is unable to
fund repairs; and (3) removal of dams which have significant environmental impact.
In a few of cases, after a dam is removed, fisheries and hospitable habitat conditions return remarkably
quickly. Dam removal alone may be insufficient to fully restore river systems, however, and may need to
be accompanied by additional measures, such as protection of native fisheries, pollution abatement,
restoration of riparian habitat, and stricter watershed management policies to increase the rate and extent
of restoration. In France, the 1998 removal of two dams on Loire River tributaries is already revitalizing
native shad, lamprey and salmon populations.
Technical Challenges in Dam Removal —Appropriate methods of dam decommissioning depend on
project attributes (such as size, type, and location of dam), river characteristics, and intended objectives
(such as fisheries restoration, land reclamation, and recreation). Dam decommissioning is, thus, highly
site-specific. Careful planning minimizes public health and safety risks to downstream communities.