Why We Are Creating Attenuation Ponds and Swales at Five Bees Farm
Water is the element that most farmers in the UK have spent the past century trying to get rid of as quickly as possible. Field drains, ditches, and culverts have been installed across the British countryside on a vast scale, all with the same objective: move water off the land and into the nearest watercourse as fast as it arrives
We are doing the opposite.
Across our 17 acres at Biteford in North Devon, we are creating multiple attenuation ponds at different points on the land, connected and fed by a network of swales that follow the natural contours of the ground. This post explains what these features are, why we are building them, and what we expect them to do for the farm, for the surrounding landscape, and for the wildlife that shares this land with us.
What are attenuation ponds and swales?
An attenuation pond is a pond designed to receive, hold, and slowly release water rather than simply collect it permanently. During heavy rainfall the pond fills, absorbing a pulse of water that would otherwise run rapidly off the land. Between rain events it slowly releases that water back into the ground or into the stream, maintaining a steady, gentle flow rather than the boom-and-bust pattern that fast-draining land creates.
A swale is a shallow channel or depression dug along the contour of a slope. Rather than channelling water downhill and away, a swale intercepts it and holds it on the contour, giving it time to soak into the ground. A well-placed swale on a sloping field can transform how that field behaves in both wet and dry conditions. Together, ponds and swales form a water management system that works with the natural movement of water through a landscape rather than fighting it.
Managing water across the whole farm
Our land at is not flat. It has slopes, hollows, and natural low points where water gathers in wet weather. In an unmanaged state, heavy rain on this kind of land moves quickly, picking up sediment as it goes, and delivers it all rapidly to the stream on our eastern boundary and ultimately to the River Torridge.
By placing swales at key points across the contours and connecting them to ponds positioned in the natural low points of the land, we slow that movement dramatically. Water that would previously have left our land within hours of falling now has the opportunity to pause, percolate, and be held within the landscape for days or weeks.
This matters for the farm in practical terms. Soil that is allowed to absorb water slowly retains moisture for longer. The water table beneath our herb beds stays higher during dry periods. The swales themselves become linear growing environments with higher moisture levels than the surrounding ground, ideal for certain species in our planting plan.
Every swale and every pond is a small intervention that changes the hydrology of the land permanently and cumulatively for the better.
Flood attenuation and the downstream benefit
North Devon has experienced a number of significant flood events in recent years. The River Torridge and its tributaries respond quickly to heavy rainfall, and the speed of that response is directly related to how much of the surrounding land is draining fast. When every farm in a catchment area has been drained and hard-surfaced to move water away as efficiently as possible, the cumulative effect downstream is dramatic. Water arrives at the river in a sudden rush rather than a gradual trickle. Rivers burst their banks. Communities flood.
A farm that holds water back, even modestly, makes a genuine contribution to reducing that peak flow. Our ponds and swales will not solve the flooding challenges of the Torridge catchment on their own. But they are part of a growing network of farms and land managers who are beginning to think about their land as part of a shared water landscape rather than as isolated units whose drainage is purely their own concern.
We think of our attenuation ponds as a gift to the valley downstream as much as an asset to the farm.
Farm resilience and drought proofing
The wet season and the dry season in North Devon are becoming more distinct. Winters bring more intense rainfall events. Summers are increasingly punctuated by extended dry periods that stress crops and deplete soil moisture. A farm that can capture and store winter water is a farm that has reserves to draw on in summer. Our ponds, at their simplest, are a form of on-farm water storage. As the system matures and the ponds fill to capacity during wet months, that stored water becomes available for irrigation during dry periods, reducing our dependence on mains water and giving us a meaningful buffer against summer drought.
For a perennial herb farm where consistent soil moisture is important for both plant establishment and crop quality, that buffer has real practical value. The swales serve a similar function from the other direction. By slowing water into the ground rather than letting it run off, they recharge the soil moisture profile across a much wider area than a pond alone would. A field with well-placed swales behaves differently in a dry summer than one without them. The difference is not dramatic in year one. Over five or ten years it becomes significant.
Wildlife habitat from the ground up
Ponds are among the most valuable wildlife habitats in the British landscape, and among the most threatened. The UK has lost the majority of its farm ponds over the past century, primarily through drainage and infill. What remains is fragmented and often degraded. A newly created pond, managed well and allowed to develop naturally, can support an extraordinary range of species within just a few years of its creation. Great crested newts, common frogs, common toads, smooth newts, dragonflies and damselflies, water beetles, and a wide range of aquatic invertebrates will all colonise a suitable pond relatively quickly if the conditions are right.
We are designing our ponds with wildlife in mind from the start. Shallow sloping margins rather than steep banks, so that amphibians can enter and exit easily and ground-level mammals including hedgehogs can drink safely. Areas of open water alongside areas of emergent vegetation where insects can breed and birds can feed. No fish, which would predate the invertebrate and amphibian communities we are trying to establish.
The ponds at different elevations and positions across the land also mean that slightly different conditions will develop in each one, with different depth profiles, different surrounding vegetation, and different sun and shade. That variety in itself supports a wider range of species than a single large pond would.
The swales, as they establish and the vegetation along their margins develops, become linear wetland habitats connecting the ponds to each other and to the wider hedgerow and stream network. A grass snake moving between the stream margin and a pond, or a water shrew hunting along a swale, can do so through continuous cover rather than having to cross open ground.
Water and the whole farm system
We do not think of our ponds and swales as separate water management infrastructure. We think of them as part of the same integrated system as our trees, our hedgerows, our no-dig herb beds, and our stream restoration work. The trees slow rainfall at the canopy before it even reaches the ground. The no-dig soil beneath them absorbs it more readily than compacted, disturbed soil. The swales intercept what runs off the surface. The ponds receive and hold what the swales cannot absorb. The stream receives a steady, clean, moderate flow rather than a violent, silty pulse. Each element makes the others work better. That is what we mean when we say we are building a system rather than a farm.
The ponds will take time to settle, to develop their margins, and to be discovered by the wildlife we are hoping to attract. But they are permanent features. In twenty years they will be mature, species-rich, and deeply embedded in the ecology of this piece of North Devon. We cannot wait to watch them develop.