ponds

Tearing down small dams to restore rivers

March 11, 2025 By EarthWise Leave a Comment

There are more than 31,000 dams in the northeastern United States. More than 4,000 of them are in the Hudson River watershed. Most of these dams are quite small and were built in the 19^th century to form ponds and to power grist, textile, paper, saw, and other kinds of mills as the region developed its industrial infrastructure. The nonprofit organization American Rivers estimates that 85% of U.S. dams are unnecessary at best and pose risks to public safety at worst.

Dam removals have been occurring for over 100 years, but the vast majority have taken place since the mid-2010s and have increased dramatically since the 2021 Bipartisan Infrastructure Law, which provided funding for such projects.

So far, 806 Northeastern dams have come down and hundreds more are in the pipeline.

Dam removals improve aquatic fish passage, water quality, watershed resilience, and habitat for all the organisms in river ecosystem food chains, ranging from insects to fish to otters to eagles. Small dams have degraded habitat and altered downstream hydrology and sediment flows. They have created warm, stagnant, low-oxygen pools that trigger algal blooms and favor invasive species.

But removing even small dams is not an easy matter. Projects range in cost from $100,000 to $3 million and qualifying for funding – whether federal or state – requires projects to meet a variety of requirements including community support. Not all dams can be removed, but many more should.

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How Tearing Down Small Dams Is Helping Restore Northeast Rivers

Photo, posted September 20, 2010, courtesy of Doug Kerr via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Forever chemicals in water

April 23, 2024 By EarthWise Leave a Comment

So-called forever chemicals are pervasive in a wide range of products. These are man-made substances called per- and polyfluoroalkyls or PFAS. They get their unfortunate nickname because the chemical bonds in them are so strong that the compounds don’t break down for hundreds or even thousands of years.

PFAS compounds are used in makeup, dental floss, nonstick pans, food wrappers, pesticides, stain-resistant fabrics and carpets, firefighting foams, and more. High level exposure to some of these chemicals has been linked to a variety of health problems include high cholesterol, liver and immune system damage, pregnancy problems, and kidney and testicular cancer.

A recent study published in the journal Nature Geoscience has found that PFAS chemicals are showing up in water around the world. The study looked at more than 45,000 water samples and found that about 31% of ground water tested that wasn’t even near any obvious source of PFAS contamination had levels of the chemicals that are considered harmful to human health by the EPA. About 16% of surface water samples – streams, rivers, ponds, and lakes – also not near any known source, had similar hazardous PFAS levels.

The EPA has now imposed strict new drinking water limits for six types of PFAS. Going forward, water systems are required to monitor for these chemicals and remove them if they are found above allowable levels. The new rules make the United States one of the strictest countries in the world in terms of regulating PFAS in water.

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EPA puts limits on ‘forever chemicals’ in drinking water

Photo, posted May 5, 2020, courtesy of Brandon Shaw via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Attack of the giant goldfish

January 15, 2024 By EarthWise Leave a Comment

Goldfish are just about the easiest pets to keep. A species of carp native to East Asia, they have been bred to look pretty and are generally little more than home décor. We keep them in little glass bowls and feed them mysterious flakes out of a container. With these confined quarters and meager meals, they remain small, harmless creatures. But released into the wild, it is a very different story.

People dump pet goldfish into lakes and ponds with some frequency. Once they are in the wild, these humble creatures can grow to monstrous proportions. They can eat nearly anything, including algae, aquatic plants, eggs, and invertebrates. They can kill off native marine wildlife and damage or even destroy fragile and economically valuable ecosystems.

For a few years, Canadian researchers have been tracking invasive goldfish in Hamilton Harbour, at the western tip of Lake Ontario, about 35 miles southwest of Toronto. That part of the lake has been decimated by industrial and urban development as well as by invasive species.

Goldfish were first spotted in the harbor in the 1960s, mostly died off in the 70s because of industrial contamination, but then recovered in the 2000s. Goldfish can tolerate a wide range of water temperatures, reach sexual maturity quickly, and can reproduce several times in one season. In resource-rich places, they can grow up to 16 inches long, making them too large a meal for many predators.

There are literally millions of goldfish in the Great Lakes and not only there. Feral goldfish are a problem in Australia and in the United Kingdom. Invasive species are a big problem, even if they start out small and cute.

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Once They Were Pets. Now Giant Goldfish Are Menacing the Great Lakes.

Photo, posted September 20, 2015, courtesy of Watts via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Beaver Believers | Earth Wise

August 18, 2023 By EarthWise Leave a Comment

Beavers are ecosystem engineers based on their ability to construct dams and create ponds. By doing so, they create wetland habitat for other species. They create biodiversity by allowing plant species to emerge in new places as they clear out existing trees and other plants. Beavers improve water quality and their dams store water during droughts. Their handiwork minimizes flood risk and mitigates flooding impacts.

Before beavers were widely trapped, there were beaver dams just about everywhere in the American west. Now beaver rewilding is trying to restore many western ecosystems. In places like Idaho, ranchers have gone from seeing beavers as a nuisance to actually recruiting them onto their land. One cattle rancher began stream restoration on his land with beaver rewilding in 2014. By 2022, he was a firm “beaver believer”. There are now over 200 beaver dams along Birch Creek near Preston, Idaho, and the stream now flows 40 days longer into the year.

NASA has established a team to investigate the extent to which beavers can have an outsized and positive impact on local ecosystems. The team is using NASA’s Earth Observation satellites to observe the effects beavers are having. Satellites can collect data from large areas and can pass over the same areas regularly and across seasons. The goal is to support people on the ground who are implementing beaver rewilding efforts to increase water availability and to increase habits for fish and other species. NASA’s project will run through 2025 and it plans to expand it to other states with similar terrain and water management strategies.

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Researchers Become “Beaver Believers” After Measuring the Impacts of Rewilding

Photo, posted February 23, 2021, courtesy of Deborah Freeman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Bengal Water Machine | Earth Wise

October 31, 2022 By EarthWise Leave a Comment

Over the past three decades, the owners of 16 million small farms in the Bengal Basin of Bangladesh have been pumping shallow groundwater during dry seasons to irrigate rice paddies. By lowering groundwater levels in this way during the dry season, the ability of leakage from rivers, lakes, and ponds to replenish the groundwater was greatly enhanced. Capturing surface water not only improved the recovery of groundwater levels but only helped to reduce flooding during monsoons.

The net result of this enormous collective groundwater pumping by millions of farmers has been the creation of vast natural reservoirs underground that are comparable to what is contained by many of the world’s largest dams. This system of sustaining irrigation has transformed what was previously a famine-prone country into a food-secure nation.

The details of this remarkable transformation have been laid out in a study by University College London recently published in the journal Science. According to the study, over the course of 30 years, more than 75 cubic kilometers of fresh water was captured by this process, which is equivalent to the combined reservoirs of China’s Three Gorges Dam and the Hoover Dam in the U.S.

The authors of the study described the water cycling process as “The Bengal Water Machine” and argue that it can be a sustainable alternative to conventional approaches to seasonal river flow storage for irrigation, which typically involve dams and reservoirs. Such approaches are difficult to implement in densely populated alluvial plains where sand, silt, and clay are laid down by annual floodwaters.

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Millions of farmers “replumb” world’s largest delta

Photo, posted February 2, 2010, courtesy of Melanie Ko via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Beavers Are Flooding The Warming Arctic | Earth Wise

March 14, 2022 By EarthWise Leave a Comment

The accelerating warming in the Arctic has transformed the region into a warmer, wetter, and more diverse environment. Warming temperatures have encouraged the increasing growth of vegetation, particularly shrubs that provide beavers with bark to eat and branches to build with. Warming temperatures also mean that lakes and streams freeze solid for shorter periods of time or not at all, allowing beavers to pursue their construction projects for longer periods during the year.

Prior to the mid-1970s, residents of the Alaskan Arctic encountered few beaver ponds. In 2018, researchers using satellite imagery mapped 12,000 beaver ponds in Alaskan tundra.

Beavers are causing major changes in the streams and floodplains that many small Alaskan villages depend upon for food, water, and navigation. As the rodents transform lowland tundra ecosystems, they are eliminating food sources, deteriorating water quality, and making it difficult to navigate waterways.

The migration of beavers across the Arctic landscape is largely a result of climate change. But it is also becoming one of the factors amplifying climate change. Scientists are trying to figure out the degree of permafrost thawing that beaver dam-and-den building is causing and how fast these defrosted organic soils will degrade and release trapped carbon and methane.

Beaver dams alter the hydrology of streams by slowing the flow, storing and spreading water to create wetlands, raising the water table, and lowering the oxygen content of the water.

Climate-driven changes in species distributions affect human well-being as entire ecosystems continue to change. Shifts in animal habitat stimulated by climate change could have profound consequences across the globe.

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Beavers Are Flooding the Warming Alaskan Arctic, Threatening Fish, Water and Indigenous Traditions

Photo, posted June 12, 2018, courtesy of Peter Pearsall/USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Snakes Near A Plane | Earth Wise

September 15, 2021 By EarthWise Leave a Comment

San Francisco International Airport is the seventh-busiest airport in the United States. In a typical year, approximately 55 million people pass through SFO on their way to destinations throughout North America and beyond.

At some point during their journey to or from the terminals at SFO, each one of those people will pass by a seemingly unremarkable 180-acre parcel of land. Surrounded by highways and train tracks, the soggy and overgrown vacant lot isn’t just home to rows of power lines. It’s also home to the world’s largest population of the beautiful and highly endangered San Francisco garter snake.

According to a recent study conducted by the U.S. Geological Survey, there are approximately 1,300 San Francisco garter snakes at SFO’s West of Bayshore property – the greatest concentration of these snakes ever recorded.

Conservationists have long known that the San Francisco garter snake was in trouble. In fact, it landed on the U.S. Fish and Wildlife Service’s very first endangered species list, which was published in 1967. Over the years, agricultural, commercial, and urban development have destroyed much of its wetland habitat, as well as much of its primary food source, the California red-legged frog. The snakes have also been a popular target for poachers and collectors.

Since 2008, SFO has been working with the USFWS on a recovery strategy for the species. Together, they’ve made enhancements to the West of Bayshore habitat, including building rainfed ponds and deepening existing wetlands. They have also added fences to protect habitat and prevent illegal collection.

But low population counts at other locations means the recovery for the San Francisco garter snake is far from over.

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Combining genetic and demographic monitoring better informs conservation of an endangered urban snake

A San Francisco Airport Site Is Crawling With Snakes—And That’s a Good Thing

Photo, posted April 16, 2011, courtesy of Brian Gratwicke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Conservation In Vermont | Earth Wise

May 6, 2020 By EarthWise Leave a Comment

In recent times, Vermont and neighboring states have been losing forest land to development at a rate of almost 1,500 acres per year. With forest fragmentation gaining ground across New England, conserving land for future generations of people, wildlife, and plants has become both increasingly important and increasingly difficult.

According to a new study published by researchers at the University of Vermont, the state has already protected a third of the highest priority targeted lands needed to protect and connect valuable wildlife habitats and corridors. The protected lands amount to 1.3 million acres.

Most of the currently conserved lands are forested. However, there are high-priority targeted surface water and riparian areas – ponds, rivers, shorelines, and wetlands – and not nearly enough of these have been protected. (Many animals require zones along waterways in which to travel between the habitats they need to survive).

The state of Vermont and a number of partners have laid out a comprehensive and thoughtful vision that would ensure that Vermont remains a good place for all forms of life in the future. The new study provides a crucial benchmark of current levels of forest protection to help prioritize future conservation actions.

Three groups dominate in responsibility for the state’s protected lands: the federal government, the state government, and private non-profit organizations. (Each of these account for roughly a third of existing protected lands).

Going forward, Vermont’s nonprofits will play an increasingly important role in land conservation, especially in continuing to protect those areas that are rich with species diversity. Nonprofits are engaging more and more deeply in restoring wetlands that were previously degraded, planting new forests along river shores, and protecting unique natural communities while also protecting working forests and farmland.

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Vermont Has Conserved One Third of the Land Needed for an Ecologically Functional Future

Photo, posted June 15, 2014, courtesy of Wesley Carr via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

China And Rare Earth Mining

September 4, 2019 By EarthWise Leave a Comment

Rare earth elements are a crucial part of much of modern technology. Everything from computers to X-ray machines and aircraft engines needs one or more rare earth elements for magnets, lenses, and other functions. The world’s tech giants such as Apple, Huawei, and Tesla depend on suppliers of rare earths.

Rare earth elements are not actually rare, but they are very expensive to extract in ways that are not extremely harmful to the environment. China has been a major source of these elements since its rare earth mining industry took off in the 1990s. The removal of rare earths from the earth’s crust, using a mix of water and chemicals, has caused extensive water and soil pollution.

Today, concrete leaching ponds and plastic-lined wastewater pools dot the hills of Southeast China. Large wastewater ponds sit uncovered and open to the elements in many places. Landslides or barrier failures can spill contaminated contents into waterways or groundwater.

Local and federal officials in China have started to shut down illegal and small-scale rare earth mining operations and have embarked on a cleanup of polluted sites. The rare earth mining cleanup operation is part of wider efforts across China to address severe problems of water, air and soil pollution.

China’s Ministry of Industry and Information Technology estimated that the cleanup bill for southern Jiangxi Province could amount to more than $5 billion. Many environmental experts and local officials say that the cost of the cleanup should not be shouldered by the Chinese government alone, but also by the rare earth industry and the global companies and consumers that benefit from rare earth technology. As rare earth mining efforts start up elsewhere around the world, it is important not to repeat the mistakes made in China.

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China Wrestles with the Toxic Aftermath of Rare Earth Mining

Photo, posted April 21, 2019, courtesy of John Beans via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Natural Mosquito Repellents

June 20, 2017 By EarthWise

With summer comes mosquitoes and our desire to keep them away from us. The most common repellents are based on the chemical DEET, which unfortunately has been found to have several health and safety problems. Up to 15% of DEET is absorbed through the skin directly into the bloodstream. Diethyl-meta-toluamide, the chemical name for DEET, has been shown to have a variety of toxic effects. Fortunately, it turns out that there are some natural alternatives which may be as effective as DEET, or possibly even more effective than DEET in keeping mosquitoes away from us.