Dams
Table of Contents
Introduction
Dams can benefit or have massive negative impacts on wildlife and humans who's homes are often destroyed to create huge lakes. They disrupt river flows, preventing species like salmon and eel from reproducing, which in turn hurts other species throughout the food chain. Dams also create conditions that produce greenhouse gases.
Functionally they can produce very reliable electricity, so long as water levels remain stable, but during heavy rains, the risk of a dam collapsing and killing peple rises. During increasingly common and long-lasting droughts, many communities have lost their primary source of electricity, and risk increasingly frequent power outages.
In addition to electricity, dams can help save drinking water for communities who might otherwise would have limited resources.
Due to the extreme damage caused by dams, and the increasingly cheap alternatives to dam power, installations of new dams has slowed, and the rate of dam removals has risen.
Negatively Impacted Species
Eel
"American eels (Anguilla rostrata) are slimy fish with long, snakelike bodies found along the Atlantic coast from Greenland to Brazil. Like many species of diadromous fish (species that migrate between fresh and saltwater), American eel populations have been declining due to various factors including habitat loss, water pollution and unnatural barriers blocking their migratory routes such as dams and weirs.
American eels have very complex life cycles. They are catadromous, meaning they spend most of their lives in freshwater lakes and rivers, and migrate to the Sargasso Sea in the Atlantic Ocean to spawn. The eggs hatch in the ocean into larvae known as leptocephali. They have bodies shaped like willow leaves and drift along the currents of the Gulf Stream for about a year. As they grow, they metamorphose into glass eels. Glass eels have the typical eel shape but have transparent bodies. They ride the tides into estuaries and begin to gain pigment shortly after entering coastal waters. Once they develop greenish brown pigment, they are known as elvers. Some elvers stay in the estuaries but many migrate upstream into freshwater rivers. They can travel hundreds of miles inland in search of ideal habitat. American eels are found as far inland as Minnesota and the Great Lakes.
American eels have the ability to cross obstacles that would otherwise be impassable. They can absorb oxygen through their skin, allowing them to leave the water if necessary to continue their journey through mud and wet grass. Once they find suitable habitat, they transform into the yellow eel stage and develop a yellowish-green pigment (Figure 1). At this stage, yellow eels can remain in these habitats for over 20 years. Once they reach sexual maturity, they become silver eels and drastically change their bodies as they begin migrating back toward the ocean. They stop feeding, their digestive systems degenerate, more blood vessels form around their swim bladders to enhance buoyancy, and their eyes and fins become larger for the long journey ahead. Once they reach the Sargasso Sea and spawn, it is assumed that they die." - Dam Removals Improve American Eel Abundance
Egrets
"Egrets, along with other wetland birds, depend on healthy river systems for food and shelter. They make their nests in the steep banks of rivers or floodplain thickets. Dams prevent the natural highs and lows of rivers They can also reduce the breeding ground of migratory fish—a key food source for egrets—and cloud the waters, making it harder for egrets to spot their prey." - WWF
Forest Animals
Mammals, birds, and tortoises in the Amazon have suffered catastrophic loss from the Balbina Dam - Impacts of Mega Dams on Forest Animals
Fresh Water Mussels
Changes in water temperature, nutrient flow and oxygen levels can make it hard for freshwater fish and shellfish to adapt to climate change which is already warming waters, increasing acidity, and removing oxygen from bodies of water. - Defenders
Hellbenders
"Unlike most species, hellbenders breathe through their skin. This makes them particularly vulnerable to sediment, pollutants and reduced oxygen levels in their environment. Nutrients and pesticides, runoff and erosion from agriculture and urban development degrade water quality; mining activities deposit heavy metals and toxins into nearby waterways; and dams and road crossings isolate populations." - Defenders: Hellbender
Humans
Irrawaddy Dolphins/River Dolphins
"All river dolphins need freshwater fish, quality water and safe migratory routes to survive. Poorly planned dams often reduce dolphins’ food supply, change water quality and destroy habitats. As dams are constructed, the dynamite and noise can harm river dolphins. Once the dam is up, increased boat traffic can lead to more injuries and deaths from collisions." - WWF
Manatees
A manatee highway was cut off due to an incomplete dam, which also impacted biodiversity throughout the river. - Defenders
Orcas
Orca rely on fish species such as salmon, due to overfishing, dams, and pollution, orcas have increasingly suffered from malnutrition. Increasingly often, pregnant mothers often give birth to dead calves, or cannot properly feed them after birth. It is estimated that 2/3 orca pregnancies failed over 7 years due to lack of food.
Sea Lions
These predators have been getting culled for eating their prey, as humans have blamed them for the low numbers of fish species that we've been over harvesting for decades, polluting, and blocking from their spawning grounds.
Seals
Many seal have been lethally targeted according to these resources from Seal Sitter.
Sturgeon
"The primary cause of reproductive failure is due to dams and other human modifications of the river. Pallid sturgeon are blocked from upstream migration, and young larval sturgeon are trapped by dams." - Wildlife Defenders
Trout
Large dams can create trout habitat where it didn't previously exist, but dams can also fragment habitats which negatively impacts fish habitats.
Tools & Guides
Dam Removal
Helping Wildlife
Converting dams to living wetlands "Dams provide an excellent opportunity to create habitat and enhance biodiversity on your property. This Information Sheet provides an overview on ways you can improve the habitat value and water quality of your dam. It also outlines what you can do to minimise the impact of your dam on downstream ecology."
The Farm Dam Handbook (PDF) "A healthy farm dam is an important resource to keep stock healthy and provide water for farming properties. It also provides a valuable habitat for local wildlife. This book provides advice to help you keep your dam in good condition to enhance the health of your property."
Land for Wildlife: Wildlife Friendly Dams (pdf) "Whether their original purpose was for watering stock, irrigation or as a landscape feature, all dams can provide habitat for a surprising amount of native wildlife. This Note discusses how, through the provision of suitable habitats, a range of fauna can be encouraged to colonise a dam. Just imagine yabbies, fish, frogs, a wide range of insects such as butterflies and dragonflies, birds, reptiles and mammals living in your dam!"
Tools to Help Fish this page explains the benefits of fish ladders, bypass systems, fish-friendly turbine design, predator control (specifically keeping predators away from specific locations with appropriate barriers), and continuing research on the topic of helping fish.
Structure Integrity & Maintenance
Dam Owner’s Guide To Animal Impacts On Earthen Dams (PDF) "Twenty-five states across the U.S. can write headlines of unsafe dam operations caused by nuisance wildlife intrusions, and many dam owners find the struggle to adequately manage nuisance wildlife at their dams a never-ending story. The tasks of proper and timely wildlife damage observation, species identification and management, and dam repair often prove to be daunting responsibilities that sometimes go unchecked, despite the good intentions of dam owners. The damages caused by nuisance wildlife often appear minor and small burrows, shallow dens, and limited erosion may not trigger a dam owner’s concern.
However, the news in many states is that “minor” damages such as these are often at the core of unsafe dam operations or outright dam failure. The dam owner is the first line of defense against unsafe dam operations. As such, the Federal Emergency Management Agency (FEMA) published this brochure to help the dam owner manage nuisance wildlife and wildlife damages at earthen dams. To reduce the risk of dam failure due to wildlife intrusions, this brochure provides information on nuisance wildlife damages, wildlife observation during routine inspections, wildlife identification, and basic damage repair. Most simply, this brochure provides dam owners with a process for observing and managing wildlife intrusion damages. Regardless of which species or damages are encountered at the dam, coordination with the State Dam Safety Official and State Wildlife Manager is recommended to ensure that appropriate and lawful dam repair and wildlife management occurs."
Organizations
Europe
North America
USA
California
California Trout: Battle Creek Hydroelectric Project "was originally developed to support the power demand of mineral extraction in Shasta County including Iron Mountain Mine near Redding. The drainage was seen as an ideal drainage for hydropower generation due, in part, to its spring-fed water supply. The project included 8 low-head dams within anadromous reaches, an additional 4 dams outside of the anadromous habitat, and a complex network of 20 diversion canals and pipelines."
South America
Amazon Watch "is a 501(c)(3) nonprofit organization founded in 1996 to protect the rainforest and advance the rights of Indigenous peoples in the Amazon Basin. We partner with Indigenous and environmental organizations in campaigns for human rights, corporate accountability, and the preservation of the Amazon's ecological systems."
Maps
International
The Global Hydropower Tracker (Interactive) "is a worldwide dataset of hydropower facilities.
The tracker catalogs hydroelectric power plants with capacities of 75 megawatts (MW) or more. It includes all facilities at this capacity threshold for operating, announced, pre-construction, under construction, and shelved units. Some data are also included for plants that are either mothballed, retired, or canceled.
Projects are the fundamental level of organization for the Global Hydropower Tracker. A given project may consist of a single turbine-generator set, or multiple turbine-generator sets. When available, information about the capacity and number of turbine(s) is included. Multiple projects that are part of a collection of related power-generating infrastructure but which should be considered different plants due to distinct physical infrastructure, geographic separation, and/or other factors such as ownership or operation are linked together as a complex."
The Global Integrated Power Tracker (GIPT) (Interactive) is a multi-sector dataset of power stations and facilities worldwide. The tracker provides unit-level information on thermal power (coal, oil, gas, nuclear, geothermal, bioenergy) and renewables (solar, wind, hydro). The tracker includes data on unit capacity, status, ownership, fuel type, start year, retirement date, geolocation, and more. Each power facility is linked to a profile page, hosted on GEM.wiki, that provides further information.
Global Energy Monitor’s eight power sector trackers provide the source of underlying data: the Global Coal Plant Tracker, Global Oil and Gas Plant Tracker, Global Solar Power Tracker, Global Wind Power Tracker, Global Hydropower Tracker, Global Geothermal Power Tracker, Global Bioenergy Power Tracker, Global Nuclear Power Tracker."
Funding
Fund Your Dam Removal "Want to remove a ‘ready to go ‘ dam but need extra funding? Try getting your removal crowdfunded!"