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Pond Creation & Management

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Pond Creation & Management
Management Guide

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Creating a pond is perhaps the easiest way to rapidly improve biodiversity in a degraded ecosystem. But it’s not always easy to understand how to create or manage them, so this guide is designed to help you understand how to have a healthy, biodiverse pond.

How Many Ponds?

There’s a common myth that bigger ponds are better for wildlife. In fact, having many ponds is usually better than having one large pond. Each system will be different, creating more diversity within the same footprint.

On our pilot project, we have 7 large ponds, dug by excavator, and numerous, hand-dug smaller ones. One of these smaller ponds is lined, but all the others are simply holes in the earth (clay). At home there are another four ponds – a tiny one in the greenhouse (keeping humidity higher), a header pond for the waterfall and two larger ponds in the front and back gardens.

Larger ponds have one key benefit – with more abundant prey, you’ll find larger predators – it’s more likely that duck, heron and egret will appear (as we have found). Essentially, a bigger space has a more complex food web. But if you watch each pond for a few hours, more birds visit the 30cm header pool for the waterfall than any of the 15m ponds at the field. Location may trump size.

Every pond varies in its water chemistry, nutrient load, plant community, wind exposure, shade and numerous other factors. This means that 3 ponds within metres of one another can be totally different ecosystems. That’s the main reason why multiple ponds are generally better for diversity than one large lake.

Water trough
Dew ponds are an alternative to a watering trough like this, which doesn't often create much biodiversity

Where to Put a Pond?

This might seem like a fairly obvious statement, but water flows downhill. Placing a pond on a hilltop might make sense if there is a shallow depression, but it will look more natural and perform more effectively if it is located at the lowest point in the landscape.

Dew ponds are a counterpoint to this – they are artificial pools, traditionally dug at the top of hills, or on the side of slopes, which catch rainwater. They are constructed from puddled clay, concrete (or liner) and used for watering plants or livestock. They may provide some biodiversity value if planted out, but care must be taken to avoid choosing plants with roots which will penetrate the liner.

Typically, people avoid creating ponds in woodland, as shady ponds have less visible biodiversity (fewer dragonflies etc), and quickly become silted up due to leaf litter. But woodland ponds are extremely valuable habitats, and they can make the surrounding area wetter and more humid in dry summer months. This can improve the growth rate of many tree species.

Ponds near homes are sometimes thought of as an issue due to mosquitos. But this problem can be averted by introducing our native Stickleback fish, which keeps the mosquito larvae very effectively under control. The fish can happily co-exist with frogs and newts if there are shallow-enough margins for tadpoles and efts to escape predation.

Rewilded pond
Shallow sloping sides will allow more plants to become established in this new pond system over time.

What Does an Ideal Pond Look Like?

There’s a common myth that there is an ‘ideal’ pond. In fact, the ideal pond is one which complements other ponds in the landscape. Either by being different enough that it creates more diversity, or by being so similar that local species can use the habitat as a stepping stone to pass through the area.

So don’t worry too much about your pond ‘looking right’ – the most important thing is not the pond design, but the inputs to the system…

  • Invasive plants can outcompete native species and make a biodiverse pond into an ecological wasteland
  • High nutrient runoff can cause algal blooms which kill off plants and animals in the water, and permanently change the pond to a green water ‘eutrophic’ system
  • High disturbance from dogs, swimming and livestock can churn up the sediment and uproot aquatic plants, turning a clear water pond into a eutrophic system
  • Pollution from farms, urban areas, roads and even flea collars can all kill off aquatic life
 

The best way to protect against many of these threats is by creating a ‘wild’ buffer zone around the edge of the pond. This will trap incoming nutrients and pollutants, while preventing livestock, humans and dogs from accessing too much of the bank. Some ‘poaching’ of soil at the pond edge can be good for biodiversity, but not more than about 5-10% of the total circumference should be eroded or compacted like this.

A deep pond with steep sides is likely to have lower biodiversity than the same depth pond with shallow, sloping sides. This is because the sloping zone which transitions from cold water to warm water is where plants take root – you’ll find a steady shift in plant species as you go deeper. Both steep- and shallow-sided ponds exist in wild ecosystems.

Some amphibians need shallow water for breeding, so a steep-sided pond is not going to be home to many newts. But steep sides can be great for some species, which like the security of nesting in banks above deep water. A mix of steep and shallow sides may be best.

A pond which dries out in summer is great for amphibians, which tend to like these habitats. It’s also good for wading birds, which forage in the soft mud. These seasonal ponds aren’t good for fish and some aquatic plants, which need long-lasting water to survive. So creating a diversity of seasonal ponds and permanent ponds is a great way to create a diversity of wildlife on your land.

Standing Open Water & Canals
Rushes poke out from a pond. These are easy to identify with the rhyme 'sedges have edges, rushes are round, grasses have nodes all the way to the ground'

What Should I Plant?

You don’t necessarily need to plant out a pond. Especially if it’s a large, clay-lined pond in a rural area – you’ll find that aquatic plants will naturally appear there over a few years. They blow in as seeds, or are carried in accidentally, attached to birds, frogs etc.

Planting out a pond is a bit of a risky business. You have to be aware that, with every plant comes the threat of introducing an invasive species. These mostly come in as a tiny, invisible fragment attached to leaves or roots. Washing plants before introducing them to your pond is a no-brainer, but won’t remove everything. Here are some species to watch out for:

  • Bulrushes (native but invasive, can be good for biodiversity)
  • Duckweeds (native, but highly invasive, tend to be bad for pond biodiversity)
  • Canadian Pondweed (non-native, invasive, tend to be bad for pond biodiversity)
  • Nuttall’s Pondweed (non-native, invasive, tend to be bad for pond biodiversity)
  • Parrot’s Feather (non-native, invasive, bad for biodiversity)
  • New Zealand Pigmyweed (non-native, invasive, very bad for biodiversity)
  • Floating Pennywort (non-native, invasive, very bad for biodiversity)
  • Water Fern (non-native, invasive, very bad for biodiversity)


A very handy, exhaustive, and somewhat exhausting, list of invasive species is available from the GB Non-native Species Secretariat. Bear in mind that invasive species can also include animals, and we’ve only focused on plants here to avoid overwhelming you with information!

Given how easy it is for non-native species to spread beyond their home, the only plants which should go in a pond are native. You can find a list of native pond plants on our sister site, Buy Native.

Grass snake
If your pond's surface looks like this, then it's time to try and stabilise the system.

How Can I Stabilise a New Pond?

There’s a process which a new pond goes through when it becomes established. The flush of nutrients and unbalanced water chemistry, accompanied by too few established plants, results in a painful algal bloom. It may take several years for your pond to work its way out of this cycle of intense summer blooms, as larger pond plants become established.

The main issue is that your water is saturated with nutrients, which, in a mature pond, would be sucked up by plants as the weather started warming up. In a new pond, there isn’t enough plant biomass, so algae, which grows much quicker than plants, takes on this role. As the algae rapidly expands in volume, the water column becomes less clear, causing algae lower down to start rotting away. Low light levels hamper the growth of plants on the bottom of the pond, and the rotting algae results in low oxygen conditions, which kills off invertebrates.

We’ve found that the pond ecosystem stabilises more rapidly if rushes (pictured above) are transplanted into the water from the surrounding grassland when a pond is created. This avoids the risk of invasive species – you’re not moving pond plants but ‘dry land’ species. Rushes can survive comfortably in up to about 50cm of water overwinter. Then they’ll also cope with drying out during summer months.

Barley straw is another method that has been found to stabilise an early pond system. It slows the growth of planktic algae – the kind which floats in the water. Other kinds of straw or hay do not appear to control algal growth, and the effect of barley is thought to be due to a natural chemical released during the rotting process. One bale per 1000m2 of water surface is the recommended dosage rate, or about 2.5kg/100m2.

Scattering native aquatic plant seeds into the pond is also effective at creating a clear water system. One of the issues with larger new ponds on clay liners is that the sediment keeps getting resuspended by waves. This creates more nutrients in the water, which encourages algal growth. Deep plants reduce the height of waves, while marginal plants minimise the impact of waves on the shore. Seeds can be scattered on the water surface.

We’ve found that a floating bog is very helpful when creating a clear water pond system…

Floating bog habitat
A floating bog might not seem very inspiring at first glance, but a closer look reveals that it is incredibly rich in biodiversity.

Create Bog and Fen Habitats

A pond is just one kind of wetland habitat, but there’s another one which you may find at the point where water flows out of the system. If the ground here is usually saturated, then you’ll have a bog or fen.

Most people call the area at the edge of a pond ‘a bog’, but a bog is a habitat where the incoming water only comes from above – from rain. If your bog is also supplied with groundwater via runoff from nearby land, then it’s a fen. You can find more information about managing each of these habitats in the Fen and Bog habitat guides.

On a smaller scale, creating a minature ‘bog’ can be a fun thing to do, which could help local biodiversity, too. There are essentially two ways of doing this, and we’re trialling both on our pilot project:

Floating Bog

If you want to get sphagnum moss established, you need a very consistent water table. These species can ‘drown’ or dry out very easily, killing them off. Yet many ponds have a wildly fluctuating depth over the year, so the only place with consistent access to water is the surface.

A floating bog is a buoyant platform which sits at water level, with plant roots dangling down into the water below. It can include sphagnum, but other plants can also benefit from this habitat – especially species like Cotton Grass, Bog Asphodel, Bistorts and Sedges, which prefer boggy conditions.

We’ve put together a detailed guide to constructing a floating bog – there are many different benefits to this system. The dangling roots create a nursery for young fish, and reduce erosion of the shoreline. The plants in the bog can become established in the pond over time, gradually finding a suitable niche. The bog itself is a mini ecosystem which can be viewed close up – fascinating to observe through the seasons.

Overspill Bog/Fen

At the lowest point on the pond’s rim, you can create a second shallow depression in the ground, which receives water whenever the pond fills up. This is most effective in ponds with plastic liners. The overflow area can also be lined with plastic or thick clay, but the depth here shouldn’t be more than 5-10cm.

To create a fen, you can infill this lined area with earth. Or to create a bog, dump a load of heather, straw or hay onto the surface, when it is filled to the brim with water. Bog plants and seeds can be pushed into the earth or plant material, and moss can be inserted strategically across the surface in the bog version. You are likely to find that birds pull this new moss out – chicken wire can prevent this happening while the habitat becomes established.

Planting Out

The best way to find out what to plant is to visit a bog near you with a Plant ID app and learn what’s growing there. You can then order these species online from specialist nurseries (some may be available from the sellers on Buy Native). The plant community living on bogs varies across the UK, so it’s worth finding plants which are present in the local landscape.

Black Poplar
Pondside trees can be beneficial for biodiversity, but they also create shade and dump leaf litter into the water, increasing the rate of silt build-up.

Pond Management

Ponds will get silted up over time unless they have a fairly consistent flow of water passing through them. So, many pond owners are tempted to ‘desilt’ the pond every few years to recreate valuable deep water/open water habitat.

Is it worth doing this? That depends on the purpose of your pond and the proximity of other ponds in the landscape. A silted-up pond is not a ‘worthless’ habitat – it is of extremely high value for many species of plant and animal. But it also tends to head towards a swamp, which can be a bit smelly, and this may not be suitable if the pond was installed for aesthetic purposes (or fishing).

If there aren’t any other ponds nearby, then losing a pond to silt can be a bad thing for biodiversity. This valuable watering hole and hub of aquatic life will be lost. In this case, it may also be worth considering desilting.

Before doing any management, it is essential to check for protected species, as their presence will legally restrict what you can do and how you can do it. You can learn more about surveys and pond management in this handy PDF from the Freshwater Habitats Trust.

While habitat management is typically done in the winter, pond management is the exception to this. In winter, pond life can be sluggish or hibernating, which can result in death when the sediment is disturbed. So it is often best to manage a pond in late summer or early autumn, when it is at its driest. Then, access is easier and any organisms which are removed during the desilting process can wriggle back into the pond.

In the absence of beavers, we’re missing one key element of pond management – tree cutting. In a wild British ecosystem, riparian (river/pond bank trees) would occasionally be felled into the water for Beaver food. But we can recreate this activity ourselves. The trees can be removed to avoid rapid build up of sediment, or left to rot down in the water – that’s up to you. It’s just worth doing it the same way as a beaver to maximise the biodiversity benefits – little and often, rather than all at once.

Raised section in pond
A webbing wall separates deep water from a shallow bed created when silt was dredged from the bottom of this pond.

Treating Nutrients & Pollutants

If you have high levels of nutrients and/or pollutants flowing into a pond, this can quickly result in sediment building up, and aquatic life may be killed off by the effects of toxins in the water. But a mini treatment wetland can easily be added to a existing pond system.

Treatment wetlands are like a delta, where slow-flowing water dumps its sediment and pollutants into a dense colony of marginal plants. Here, a beneficial community of microorganisms treats pollutants, and the excess nutrients in the water are sucked up by plant roots. Microplastics are also deposited, along with harmful chemicals and pharmaceuticals, into the sediment.

At a point where runoff flows into your pond – a gulley or inlet – you can create a small wetland to treat incoming water. This will have the ‘delta’ effect, slowing incoming water and letting pollutants drop out of suspension. To do this, you’ll need to plant a dense mat of marginal plants.

Common reed, bulrush (highly invasive) and sedges can all have a similar effect of creating this treatment wetland. Reed is perhaps the most effective, though it does tend to slowly take over if it isn’t managed.

The sediment dredged from the bottom of a pond during desilting can be reused to create a revetment at the inlet. This will raise the height of the pond bed to near the water level, slowing the water flow and creating a larger area for your treatment wetland (see pic above). The sediment can be held in place with Nicospan webbing, into which wooden piles are driven to hold this underwater ‘wall’ in place.

 

Fox on rewilded pond
Ponds don't just attract aquatic wildlife, but terrestrial species like this fox, too! It's licking water on the ice in midwinter (the date is off!).

Tips for Ponds

  • Every pond needs a low point on the bank, with shallow sediment or a ramp, where mammals which have fallen in can climb out. This is equally true for humans as it is for hedgehogs!
  • Ponds on agricultural land technically require planning permission. Some councils will ignore a planning application for a pond, but failing to submit one could result in issues further down the line.
  • Landowners can get new ponds installed for free, without dealing with the hassle of planning, if they request a Great Crested Newt pond. These are available across much of the UK, in partnership with developers, who pay to offset local losses of pond habitat.
  • As in most cases, a more diverse collection of plants will typically create more diversity of other species. There are so many types of pond plant around – you can usually collect seeds or fragments of vegetation in the wild if the plant is not protected or on protected land. Just be very wary of invasive species, and wash before you introduce a plant!
  • If you see a tiny fragment of duckweed, remove it and scour the pond for any other pieces. It only takes one leaf to cover the entire surface in a matter of months. Once established, it’s practically impossible to remove.
  • Ponds have the opposite effect to drainage ditches. Because water is sitting on the land for longer, it seeps into the soil, so the surrounding area will become wetter. This might seem counterintuitive at first.
  • Ponds don’t just attract aquatic species – you’ll also find that many land-dwelling animals are drawn in, from foxes to deer, and birds galore!

Further Reading

The Freshwater Habitats Trust is a fantastic source of information about pond management and creation. This is their hub of advice on ponds.

In 2023, I gave a talk to the Chartered Institute of Ecological and Environmental Management on the role of ponds in ecosystem restoration. You can find an illustrated transcript on my ResearchGate account (click ‘View Full Text’).

 

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