In the 2012 President's Budget Request, the National Biological Information Infrastructure (NBII) is terminated. As a result, all resources, databases, tools, and applications within this web site will be removed on January 15, 2012. For more information, please refer to the NBII Program Termination page.
Dams are a commonly used technology for harnessing hydropower from flowing water. Hydropower dams vary in design, operation, and scale, and therefore have different impacts on local aquatic ecosystems, fisheries, hydrology, and geomorphology. Dams have the potential to negatively affect fish populations, especially for those species that migrate up and downstream as part of their life cycle (such as many salmon and trout species). Dams can block these migratory pathways unless there is a fish ladder or another mechanism which allows fish to move around the dam. Even with these mechanisms in place, water temperature and physical changes to rivers as a result of dams can continue to affect fish migration.
In some instances, the benefits of a dam no longer outweigh its maintenance cost, or the structure is worn down and weakened, so that removal of the dam is necessary for economic or safety reasons. Dam removal, or decommissioning, can be expensive and must be well-planned out. However, rivers and fisheries can recover relatively quickly from the effects of a dam, with normal ecological processes resuming soon after.
Wave energy is a form of clean and renewable energy that harnesses the vast amounts of energy stored in the rise and fall of ocean waves, while emitting no greenhouse gases during the production of electricity. Wave and tidal energy facility research and implementation is a newer development in renewable energy. The effects on fisheries and aquatic resources are still unknown, although potential concerns include food chain disruption, migration disruption, changes in predator/prey interactions, sediment movement, and changes in shorelines. Pilot projects are currently underway, from which scientists can determine the effects of this new renewable energy technology.
A wide variety of organisms utilize aquatic environments. They range in size from microscopic protozoa to the enormous sperm whale. Many aquatic organisms spend their entire lives in water, either in freshwater streams, rivers, and lakes, or in marine or estuarine habitats. Other aquatic organisms only spend part of their lives in water. With so many types of aquatic habitats and organisms, there is potential for renewable energy projects to impact them:
Biofuel power plants sometimes intake water from lakes or rivers, which may have direct effects on aquatic life, channel morphology, water levels, or water temperature.
Geothermal energy production may result in water pollution, depending on the type of system used. Metals, minerals, or gases can leach out from the extracted steam or hot water. Sometimes local water sources can become contaminated by the heavy metal or toxic mineral byproducts of geothermal energy production.
Hydropower can have a large and direct impact on fisheries and aquatic resources. Migration patterns can be disrupted by dams or other man-made obstructions, preventing fish access to upstream spawning areas. Hydropower facilities can change water temperature, chemistry, flow characteristics, silt load, and in-stream habitat both upstream and downstream. Reservoirs, dams, and water use associated with hydroelectric facilities can have variable and potentially wide-ranging environmental impacts on aquatic resources.
Solar energy production can require the use of toxic materials or toxic chemicals for the manufacture of solar photovoltaic cells. The manufacture also requires the use of water, which may affect aquatic ecosystems depending on the amount used and disposal of wastewater.
Wind energy turbines also require water for manufacture, and may thereby affect aquatic ecosystems.
Milltown Dam Removal
Milltown Dam, Montana [Photo: U.S. Environmental Protection Agency]
The Milltown Dam, located outside of Missoula, Montana, is a dam whose removal and restoration was initiated in 2008. The removal of Milltown Dam was a victory for healthy aquatic habitats, fisheries, and communities, and was endorsed by the EPA, the Montana Department of Fish, Wildlife, and Parks; U.S. Sen. Max Baucus; state and local governments; non-profit conservation groups; and citizens and businesses in the communities near the Milltown Reservoir. The dam was slated for removal because it was outdated, and produced very little electricity in comparison to the many ecological impacts it produced. Tons of toxic waste were held above the dam, washed downstream and collected at the dam since 1908 from upstream mining activities. The dam was identified as being at risk of structural failure, and needed many expensive updates. Local fish populations, including the federally listed bull trout
(Salvelinus confluentus)
and native westslope cutthroat trout
(Oncorhynchus clarkii lewisi)
were at risk from toxic pollution, introduced species, and blocked or constrained migration to spawning grounds. Current work on the dam removal, and restoration (including the removal of toxic sediment and reconstruction of the river channel) is on target, and is scheduled for completion by October 2010.
Over 400 dams have been removed from the rivers of America in the past twenty years, most of which were small structures that produced little electricity and were generally outdated. Dam removal provides many benefits to aquatic habitats, including the restoration of fish passage, reconnected access to spawning areas, improved and interconnected fish populations, and the recovery of the stream channel and associated hydrologic processes to a natural state.
Species Spotlight
Coho Salmon [Photo: National Oceanic and Atmospheric Administration]
Coho Salmon Oncorhynchus kisutch
Description:Coho are a large salmon that can weigh over 20 pounds. Anadramous, they live in the ocean as well as inland waters. Both ocean and inland salmon are shades of dark blue and green with silvery sides, turning red when spawning. Juvenile coho salmon have sickle shaped anal and dorsal fins that distinguish them from other salmon species.
Life History:Coho travel to small inland coastal streams in September for spawning, usually laying at least one hundred eggs at each spawning site. The eggs incubate from November until around April, and the juveniles (or parr) gradually move to deeper water after hatching. After a year of rearing in fresh water, they typically move to marine waters, where they usually spend two to three years before returning inland to spawn.
Habitat:Live in inland waters as well as coastal waters. Mature coho spend their time in inland fresh water streams for spawning from September until January.
Distribution:Coho salmon are found along the Pacific Ocean coast, from the northern half of the California coast, through Canada, and into Alaska. They are also found in Russian and Japanese coastal waters.
Status:Coho populations are currently listed as threatened or endangered by the U.S. Fish and Wildlife Service due to factors including urbanization, road construction, water quality degradation, dams, and water diversion.
Resources:California Department of Fish and Game, Fisheries Resources and Species Management- Coho salmon
Featured Fisheries and Aquatic Resources Resource
For more information about fishes nationwide, visit the NBII Fisheries and Aquatic Resources (NBII-FAR) web site. There you can find further web resources on fishes and aquatic organisms and the diverse factors affecting aquatic resources nationally.
![Glen Canyon Dam [Photo: National Renewable Energy Laboratory Image Library]](https://cybercemetery.unt.edu/archive/nbii/20120111160753im_/http://www.nbii.gov/portal/server.pt/gateway/PTARGS_0_2_26431_1956_7166_43/http%3B/cbi-lap7.cbi.cr.usgs.gov%3B7097/publishedcontent/publish/ecological_topics/renewable_energy_project/impact_of_dams/renew_dams_and_fisheries__narrow__1.jpg)
![[Image: Oak Ridge National Laboratory]](https://cybercemetery.unt.edu/archive/nbii/20120111160753im_/http://www.nbii.gov/portal/server.pt/gateway/PTARGS_0_2_26929_1956_7166_43/http%3B/cbi-lap7.cbi.cr.usgs.gov%3B7097/publishedcontent/publish/ecological_topics/renewable_energy_project/wave_energy_impact/renew_wave_energy_impacts_highlight__narrow__1.jpg)
![Coho salmon fingerlings [Photo: NREL Image Library]](https://cybercemetery.unt.edu/archive/nbii/20120111160753im_/http://www.nbii.gov/portal/server.pt/gateway/PTARGS_0_2_26491_1956_7166_43/http%3B/cbi-lap7.cbi.cr.usgs.gov%3B7097/publishedcontent/publish/ecological_topics/renewable_energy_project/fisheries_and_aquatic_resources_intro/renew_fisheries_and_aquatic_resources_3.jpg)
![Milltown Dam, Montana [Photo: U.S. EPA]](https://cybercemetery.unt.edu/archive/nbii/20120111160753im_/http://www.nbii.gov/portal/server.pt/gateway/PTARGS_0_2_26859_1956_7166_43/http%3B/cbi-lap7.cbi.cr.usgs.gov%3B7097/publishedcontent/publish/ecological_topics/renewable_energy_project/dam_removal/milltown_dam_removal_1.jpg)
![Coho Salmon [Photo: National Oceanic and Atmospheric Administration]](https://cybercemetery.unt.edu/archive/nbii/20120111160753im_/http://www.nbii.gov/portal/server.pt/gateway/PTARGS_0_2_26793_1956_7166_43/http%3B/cbi-lap7.cbi.cr.usgs.gov%3B7097/publishedcontent/publish/ecological_topics/renewable_energy_project/energy_and_environmentl__coho_salmon/renew_coho_salmon_species_spotlight_for_fisheries_and_aquatic_resources_page_1.jpg)
