The planet-saving power of ponds

In the push to save the planet, you might be surprised to learn that the impact of well-funded, centralized, industrial efforts may be outshined by the effects of the humble pond. 

Municipalities from Corvallis, Oregon all the way to Wakefield in West Yorkshire, England are praising their local ponds for everything from increasing biodiversity to saving them water. Some experts even say that adding a pond to your landscape can actually cut your water bill. But who showed us that putting power in the hands of individuals (and their ponds) can have such an impact? One of nature’s original engineers – the beaver.

Beavers: unsung heroes

Andrew Millison is a big fan of beavers. He makes his living educating Oregon State University students in permaculture design, but Internet audiences around the world now recognize him as an expert in permaculture water management. He offers top-notch, free resources on permaculture to help us all collectively pay it forward.

And people are listening. Millison’s YouTube channel has 236K subscribers and 21+ million views, and his Earth Repair Radio podcast has thousands of listens. So, it’s fair to say he’s made a splash in the permaculture scene, emerging as a trusted voice in conservation.

Central to Millison’s point of view is that beavers play a central role in creating and maintaining healthy ecosystems by turning degraded landscapes and bionetworks back into food-rich, water-rich, nature-rich environments. Beavers use their formidable choppers to knock down trees and gather branches and mud to make dams across rivers and streams, and these “leaky dams” create aerated ponds that filter out larger sediment and provide places for beavers to construct protected lodges. These obstructions slow the flow of water considerably, allowing it to seep into underground aquifers (or reservoirs) through tiny holes in the sediment layer, which filters out more contaminants, and benefits local ecosystems and the animals and humans who live there. 

Unfortunately, the beaver population in the US has suffered a massive 80%-98% decline since European settlement. This represents a loss of millions of dams (and ponds) nationwide. It would behoove us humans, as Millison says, “to think like beavers, act like beavers, and take the place of beavers in our design, development, and restoration of degraded landscapes around the world. We need to heal the planet with ponds.” It’s time to bring the beavers back.

A pond by any other name

So, what makes a pond a pond — and not a lake? Both are inland bodies of freshwater that provide shelter for living creatures, but ponds are usually much shallower and smaller in surface area than their bigger-bodied counterparts, with much gentler waves, if any. The shallow depths of the permaculture pond allow sunlight to reach its lowest levels, helping uniform temperatures to prevail and plants to thrive throughout the entirety of the pond. 

While there is some disagreement over the size and depth distinctions between lakes and ponds, we can typically break the types of permaculture ponds into six main categories: 

• Seepage ponds have loose-soiled, unstable embankments that let water seep into and hydrate the surrounding landscape.
• Irrigation ponds have non-porous or compacted linings that let water accrue during the rainy season for crop irrigation during the growing season.
• Recreation ponds stay full throughout the summer for swimming and other activities and can be repurposed into skating rinks in the winter. They may have plants in the shallower ends that filter and clean the water.
• Firefighting ponds are placed at higher locations in the landscape so that they can feed firefighting systems using gravity, not electricity (which can go out during fires). Like irrigation ponds, their linings let water accrue so that they’re more likely to stay full throughout the dry season. 
• Habitat ponds have varied water levels that fluctuate seasonally and enable plant, insect, aquatic, and animal species to thrive year-round.
• Aquaculture ponds have human-controlled inflow and outflow of water, enabling the harvesting of specific species of fish during appropriate seasons.

Ponds often overlap categories, making these bodies of water wonderfully versatile. As Millison notes, all ponds built in the right place, way, and climate have great potential to shift the ecosystem and hydrology of an area for the better. However, if biodiversity is the goal, habitat and aquaculture ponds are the clear stars.

The watery cycle of life

When beavers make dams, they slow the flow of water and create seepage ponds that soak into the surrounding landscape and passively water crops in low-level areas. The result is a widely spread wetland with a habitat pond that attracts all sorts of waterfowl. In temperate areas, this newly wet landscape also encourages the growth of edge plants, which in turn attracts more wildlife for grazing and pollination. 

Aquatic plants also flourish in these conditions, providing food and protective spawning grounds for aquatic life, while helping to maintain water quality and oxygen levels. Moving channels of underground water and shaded landscapes further regulate the temperature of this naturally calibrated water, making these ponds strong choices for fisheries. Millison points out that, perhaps best of all, ponds can naturally filter out larger pollutants and sediment before they hit aquifers, which helps contribute to healthy conditions for fish. These ponds hold onto vital nutrients instead of pushing them downstream and out into the ocean, creating a cycle of more plant growth, wildlife expansion, decomposition — a watery cycle of life. 

Stemming (and saving) the rain

Connected to the irrigation systems of farms, irrigation ponds not only collect rain in the wetter seasons to help keep farms thriving in the drier season, they also attract livestock looking for water. Rain is not always a blessing, though, especially when too much of it at once leads to flooding. 

The 2023 storms and subsequent flooding in California highlighted a missed opportunity of capturing record-level rainfall and making it useful to a drought-stricken state, instead of letting it go to waste. And that’s a shame because stormwater management ponds (aka detention basins, which temporarily hold water, and retention ponds, which permanently hold water) are critical for storing excess rainwater to help restrict the rush of stormwater that would otherwise flood downstream areas and carry pollutants to nearby waterways.

Small is good, too

Residential or garden ponds are also seen by some as environmental boons, especially if made porously (without plastic sheeting) to mimic the filtering and recharging effects of beaver dams. Experts estimate there are as many as 3 million garden ponds in the United Kingdom alone. These small-scale water features cool down their surroundings far more than decorative rocks and stones do. They also use less water than lawns (as much as 80% less, according to one estimate) and provide protection for animals impacted by drought. 

Ready to build a pond?

Start your research with the EPA’s general advice, see how rural folks do it, and make sure you know your local rules/guidelines. Once you know it’s possible, this guide from the Alabama Cooperative Extension System is very comprehensive. Your locale may have their own advice – seek it out. Don’t forget to decide which edge plants will help your pond succeed.

Ponds vary in color, depth, and plant life, so they attract different species even if they’re all in the same neighborhood. And while agricultural ponds have a higher conservation value than garden ponds, residential ponds still make a significant contribution to the ecological diversity of urban pond networks, according to a study published by geologists at University of Huddersfield in the United Kingdom.

… when installed with care

Despite the evidence favoring ponds, some see them, especially larger-scale industrial ponds, as playing their own role in spurring climate change. Scientists at the University of Exeter and Queen Mary University conducted a study in 2017 that found increasing environmental temperatures led to a spike in methane and decrease in carbon dioxide released by ponds. Researchers at the University of Minnesota discovered that floating plants like duckweed increase this global warming effect by preventing the production of oxygen.

But avoiding such plants, installing fountains for aeration, and clearing surrounding trees to increase wind speeds can help mitigate these negative effects. In addition, ponds with the highest ecological value appear to be natural (not industrial) ones filled by rainwater, not tap water. So it may be best to dig, sit back, and wait. 

Don’t leave it to beavers

With the growing body of research on the positive impact of ponds on the environment, various organizations have formed across the globe to promote these shallow bodies of water. The EU-funded Pond Ecosystems for Resilient Future Landscapes (Ponderful) and the Rwanda Biodiversity Information System (RBIS) are just two initiatives aimed at collecting pond data and educating the public. Others, like the U.K.-located Norfolk Ponds Project (NPP), are working on restoration and conservation to keep the number of environmentally friendly ponds stable in their regions.

One thing is certain: we can no longer rely on our friends the beavers to dam up the landscape and help fight climate change. It’s up to us humans to start digging. 

Read more about beavers

• You can read about one man’s very funny and insightful mission to bring beavers back to the UK in Bringing Back the Beaver: One Man’s Quest to Rewild Britain’s Waterways.
• Did you know there is a phrase for this kind of surreptitious rewilding? It’s called “beaver bombing” in radical conservation circles, releasing beavers back into the wild. Where do they get such beavers?  Read about the “the Pablo Escobar of beavers” in The secret movement bringing Europe’s wildlife back from the brink.
• Read an excerpt from environmental journalist Ben Goldfarb’s Eager: The Surprising, Secret Life of Beavers and Why They Matter.