Dams

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.

Pallid SturgeonPallid sturgeon are one of the largest freshwater fish in North America, characterized by their bony plates and pale appearance. They are an ancient 'dinosaur fish' whose ancestors date back 78 million years. For generations, the pallid sturgeon swam freely in rivers from Montana to New Orleans. But dam building in the 1900s disrupted the rivers’ natural sediment, flow, temperature and oxygen levels. This destroyed and cut off access to much of the sturgeon’s spawning grounds. They might swim hundreds of miles upstream to spawn, and their eggs float back downstream until they hatch. Unfortunately, most of these eggs end up in man-made reservoirs where they sink to the bottom of oxygen-deprived reservoirs and die. For possibly as many as 60 years, no wild-born pallid sturgeon—protected as an endangered species since 1990—has survived to adulthood.

4 Species Impacted by DamsMany freshwater species depend on free-flowing rivers to complete their life cycles, and in some systems, those species make up critical parts of people’s diets. Here’s a look at five important species impacted by dams.

Blocked Migration: Fish Ladders On U.S. Dams Are Not Effective Fishways on rivers in the U.S. Northeast are failing, with less than 3 percent of one key species making it upriver to their spawning grounds, according to a new study. The researchers’ findings provide a cautionary tale for other nations now planning big dam projects.

NOAA Warns: Don’t Shoot Seals or Sea LionsPenalties include up to $28,520 and/or one year imprisonment.

HellbenderSometimes known as the “devil dog” or “snot otter,” the eastern hellbender is North America’s largest salamander. A fully aquatic species, hellbenders have inhabited the rivers of the eastern United States for the last 65 million years and are indicators of healthy streams. But without direct intervention, they could be headed for extinction. Hellbenders require very specific habitat conditions to survive. In addition to clean, oxygen-rich water, they need access to prey, the ability to find mates, and large slab rocks with accessible crevices underneath to make homes and protect maturing eggs. Humans have dramatically changed and polluted the landscape, leading to declines in habitat and water quality that now threaten the hellbender’s survival.

Dams and trout: the good, bad and uglyThere is not a simple answer regarding dams and their impact on trout and salmon populations and fishing opportunities. It all depends on the type and operation of the dam itself.

Dam it! Dams, Damage and DefendersJoin us on a cross-country road trip for World Water Week! Similar to how major roads and highways can block access to habitat for land animals, dams and diversions harm river connectivity, acting as physical barriers for wildlife.

Tools & Guides

Dam Removal

Exploring Dam Removal: A Decision Making Guide (PDF)

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

Dam Removal Europe

This organization is offering a dam removal seminar in 19 – 21 May, 2022, Lisbon, Portugal.

Home - Dam Removal EuropeMany dams in European rivers are old, abandoned and out of use. Together we can locate and remove them. Do you want to remove a dam? We can help!

Battle Creek DamsBattle Creek Dams

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."

Funding

Fund Your Dam Removal "Want to remove a ‘ready to go ‘ dam but need extra funding? Try getting your removal crowdfunded!"

Fund your dam removal - Dam Removal EuropeTo see if crowdfunding is the right option for you, read below and also have a look here to see what previous campaigns looked like. Below is a list of information we require to help fundraise for your dam removal separated into three phases.