Creating new ponds and wetlands helps in a small way to replace lost habitats. They are a fairly reliable way of attracting wildlife. Digging, filling and stocking a pond is an enjoyable project, and most small ponds will require some annual maintenance, which helps maintain interest. Ponds and water are a great attraction for children. If there is a problem with safety, or vandalism, it may be possible to build a small water feature such as an artificial ‘spring’, which may be appropriate for school grounds or the garden of a community centre.
Consultation
Consult with the local community. There may be safety considerations, though most ponds will be on sites where small children would normally be closely supervised.
Any school pond will require consultation with the education authority and school governors.
What sort of pond? A small wildlife pond is not compatible with keeping fish or ducks, and some local residents may prefer an ornamental pond of mainly open water. It may be possible to reach a compromise by creating a small pond for fish, separate from the wildlife pond. Ornamental features such as waterfalls and bubble fountains can be incorporated to improve the quality of water in wildlife ponds, although these add to the expense and maintenance requirements.
If the water supply to the pond is to be taken from a stream, river, spring or well, you will need to consult with the Environment Agency or equivalent (see below).
Survey
Carefully survey the site, in order to choose the best location for the pond. The following points need consideration:
Existing habitat
Existing damp grassland or a damp hollow may already be a valuable habitat, which pond creation would destroy. Also avoid the need for felling trees, especially old ones, in order to create a pond.
Normally avoid sites which naturally gather rainwater flowing off the land, as these will flood after storms, and rapidly fill with sediments. If using such a site, silt traps and an overflow channel will be necessary.
Ground conditions
Dig some test pits to see what the ground conditions are like. In urban areas you may find the ground is very disturbed, with remains of old buildings, drains and so on, which may make excavation difficult. Disturbed ground may also contain pollutants, toxic material or methane gas. Ask for advice from the Environment Agency if problems are suspected.
Underground services, including gas, electricity, water supply and drains may cross the site. Check their locations with the local supply companies and local authority.
Natural water supply
Ponds can be fed naturally from a high water table, from a spring or stream, or from drainage off the land or from buildings.
A high water table will be indicated by waterlogging in winter, and marshy ground in summer. A simple excavation below the level of the winter water table will create a pool which will be flooded in winter, with the water level dropping during the summer months. This drying out is not necessarily a problem, and the pond will provide a valuable habitat.
A spring or stream can be diverted, or a supply taken from it, to fill a pond. This ‘abstraction’ of water requires a licence from the Environment Agency or equivalent. It is not normally a good idea to excavate the stream bed to create the pond, as it will rapidly silt up. An ‘off-stream’ pond, which takes water diverted from the stream is a better arrangement. A sluice or some method of controlling the level of water will be needed. For further details see Waterways and Wetlands – Dams, weirs and sluices.
Ponds filled from overland flow of rainwater running down slope will rapidly fill with sediments. In urban areas, a source which is increasingly being used is the rainwater which falls on hard surfaces, and normally runs away in storm drains. Some of this can be diverted to create new ponds or other water features. The water first needs to be cleaned of pollutants, particularly oil residue and dog faeces, by passing it through an area of reedbed or marsh.
A cleaner source is to use rainwater from the roofs of buildings. This can be fed directly into ponds and marshes. An overflow system to divert storm water flows should be installed. no permission is required to collect this source of water, and a system can be easily constructed from materials available from DIY stores.
Mains water supply
Many small ponds with artificial linings are filled from the mains supply. The fire brigade may help with initial filling of school or community ponds if it is at some distance from a tap. The water level will drop due to evaporation during the summer. Topping up using rainwater gathered from roofs or hard surfaces, or from the mains supply may be desirable to prevent the liner becoming exposed and prone to damage. Where hosepipe bans are in force, topping up of wildlife ponds is not permitted. Topping up ponds containing fish is allowed even during a hosepipe ban, because fish are classified as livestock.
Design
Where an artificial lining is being used, simple oval shapes are the easiest and most economical to construct. Varying edge treatments, including boardwalks for dipping, gravel beaches, marginal planting or areas of marsh will give interest to the basic shape.
The size will depend on the space available, and on the resources for excavation and purchase of the lining material. Wildlife ponds intended for amenity and educational use need to be of sufficient size to support a stable but diverse plant and animal community. Where possible, a pond of 40-60 square metres with an additional marsh area should be the aim. However, much smaller ponds can be valuable wildlife features and are well worth constructing. Even a small garden pond of only a few square metres can support populations of invertebrates, provide spawning areas for amphibians and a drinking place for birds.
The maximum depth to support a range of wildlife need be no more than one metre. By far the most valuable part for wildlife of any pond or lake are the margins down to about one metre. For safety, the following guidelines are recommended by Surrey County Council for schools, aimed at ensuring that no pond is too deep for a child of the relevant age to stand up in:
- Secondary schools: 1 metre maximum
- Junior and middle schools: 600mm maximum
However, ponds of this depth are likely to require more frequent maintenance than deeper ponds, if they are to retain some open water. Be prepared to do some clearance of vegetation every autumn, and ensure that silt cannot wash into the pond.
The pond can either be constructed with a simple dished profile, or with planting shelves at a variety of depths, on which the marginal and emergent plants can be planted. Whatever type of lining you use, make sure that the lip of the excavation is level, so that at no point is the lining exposed when the water is at maximum level. For small ponds, knock pegs in around the perimeter of the excavation and check with a spirit level.Alternatively, use a length of transparent tube, filled with water, to level across the site. On larger ponds, use surveying equipment.
A marsh area can be constructed with the same type of lining as the pond, laid to a maximum depth of about 500mm, and then backfilled with soil.
Types of lining
Concrete
Concrete is very durable, and resistant to damage by drought, ultraviolet light and vandals. However, most methods of construction require skilled labour, and damage from frost or ice is difficult to repair. new concrete ponds must be filled and emptied several times to remove solutes from the concrete which are harmful to wildlife. The water should be suitable once the pH drops below 8.5.
The vandal-resistant quality of concrete may make it the only option in some areas. It also allows easy maintenance of the pond, because the concrete cannot be damaged by people wading in or using rakes. Hampshire County Council, working with TCV, have developed a method of laying concrete into a honeycomb geotextile fabric, marketed as ‘Armater ’. This can be done by unskilled labour. The concrete functions only as a protective layer, laid over various layers as shown, to protect the main waterproof membrane below. For further details, see Waterways and Wetlands – Concrete linings.
Puddled clay
Clay, puddled to a plastic consistency, is the traditional method of lining ponds and canals. The clay is obtained from a suitable local source, spread over the excavation, mixed with water and then repeatedly trampled to remove all the air spaces and to break down the structure of the clay. Puddling is hard work, and must be done thoroughly to make a waterproof seal. In the past, flocks of sheep were used for puddling canal and pond linings. A modern method is to use a dumper truck or JCB, driven back and forth.
A puddled clay lining is feasible if there a suitable source of clay, and access close to the site. Clay may be available cheaply as a waste product from local building development work. Contact local haulage operators or waste disposal services to find out if any is available, but you will have to take it at a time that suits them. Clay producers or suppliers of aggregates should be able to supply at any time.
The clay layer should be at least 150mm (6”) thick, and at least one third extra by volume should be ordered as the clay is supplied unconsolidated. Once properly puddled, the clay lining remains waterproof indefinitely, provided it remains underwater. Exposed clay dries out and cracks. For further details on puddling, see Waterways and Wetlands – Puddled clay.
Butyl lining
Butyl rubber is a flexible, waterproof sheet material, available from pond suppliers in a range of thicknesses. It is much easier to lay than concrete or clay. Its main disadvantage is that it is vulnerable to accidental or malicious damage. It may also become exposed to damage by ultraviolet light if water levels drop. For small ponds in schools or other areas with some supervision it is the usual choice.
The butyl should be protected from beneath by a 20mm layer of sand, and by layers of damp cardboard, newspapers or carpet on the slopes where sand will slip. A layer of geotextile, which provides some protection against damage and helps prevent the soil layer slipping, can be used over the butyl. At Hollybush Farm, Leeds, TCV have used a second layer of carpets and a tarpaulin over the butyl layer, as further protection. Vandals may manage to puncture the ‘first line of defence’ of the tarpaulin, but the butyl layer remains undamaged beneath. When using old carpets, remove the tacks. If using over the butyl, allow for a generous coverage of soil, to prevent the dye leaking through. Excavate to a sufficient depth to allow for the thickness of the layers, and keep profiles and pond shapes simple as detail will be lost in the construction.
Another method of protecting butyl from vandalism is to use a layer of old bricks, which can normally be obtained free from demolition companies. Cover the butyl with a 100mm layer of sand, and over it place a layer of bricks, butted up as neatly as possible. Cover the bricks with soil. This layer is not only difficult to puncture, but makes a good anchorage layer for plants.
Further details on the installation of flexible liners should be obtained from the supplier.
Rigid linings
Pre-formed glass fibre pools are available from garden pond suppliers. These are light, easy to install and fairly vandal-resistant but expensive for the volume of water they contain. Various other containers such as disused water tanks, baths, large plastic containers or barrels can be used to make mini-ponds, either sunk into the ground or up against a bank to allow access for amphibians. Bricks or rocks can be added to vary the depth and make planting shelves.
Artificial spring
Where safety or vandalism are particular problems, the following construction may be suitable. There is no open standing water, but the flowing water provides a damp area which will attract birds, amphibians and other small creatures. The system will need topping up occasionally due to evaporation. Apart from the submersible pump and electrics, the remainder can be built from scrap materials. An artificial spring needs to be near an electric supply, but can either be a ‘natural’ feature surrounded with grass and shrubs, or set in a paved area.
Set a disused water tank or similar into the ground, and have the pump and electrics installed by a qualified
person. Fill the tank with water. Cover with a metal grid or similar, strong enough to support the weight of material above. Depending on the mesh size, cover with a thick plastic sheet with sufficient small holes to let the water run through. This is necessary to prevent amphibians and other creatures from falling into the tank.
Build the feature above out of a ‘millstone’, which you can cast out of concrete in a mould, or by a paving slab or solid piece of timber with a hole drilled through. Arrange rounded boulders, rough rock, old bricks, pieces of timber or other suitable material onto the grid. These can be secured by blobs of mortar as necessary, but ensure there are enough gaps to let the water run through.
During dry weather, running the pump at night and through the dawn will benefit amphibians and other nocturnal animals, as well as the early wakers.
Planting
Plants will eventually colonise a new pond, but on most sites planting will be worthwhile. This allows you to choose the species you want, gives immediate visual interest, and is an enjoyable part of a pond creation project. Some areas should be left as bare mud or shingle. These are important habitats for invertebrates, and provide places for birds to drink and gather mud for nesting. Trampling may be sufficient to keep such areas open.
Pond plants can be obtained, with permission, from nearby ponds of the type you wish to recreate. Plants can be pulled or dug out in the late spring, or saved and replanted during vegetation clearance work in the autumn.
A new pond, whether of concrete, butyl or puddled clay, must have a layer of soil over the liner in which the pond plants root and pond organisms live. Use subsoil, rather than fertile garden soil, and spread it in a layer about 100mm thick over the liner before filling with water. New concrete ponds, which need filling and emptying several times should not have the soil added until the water pH is below 8.5, otherwise the solutes get ‘locked up’ in the soil. Scatter the soil over the water surface, and allow it settle for a few days before planting.
Wellies are necessary footwear for planting marginals. Submerged species can be planted by loosely wrapping the roots in some sacking, old tights or similar, weighted with some soil. Loosely fasten with a rubber band or biodegradable string, and then throw the plant into the water, where the sacking will eventually rot. Lilies should be planted in a mesh basket, and lowered into the deeper water in stages over a couple of weeks, to allow the leaf stems to grow up to the water surface.
The plants listed below are recommended for medium- sized wildlife ponds. The groupings are for guidance only, as many water plants are tolerant of varying water levels and grow across a range of conditions, sometimes showing different forms of growth according to the conditions.
Marsh and bankside plants
Forget-me-not (Myosotis spp)
Meadowsweet (Filipendula ulmaria)
Purple loosestrife (Lythrum salicaria)
Ragged robin (Lychnis flos-cuculi)
Water mint (Mentha aquatica)
Marginal plants
Greater pond sedge (Carex riparia)
Marsh marigold (Caltha palustris)
Water forget-me-not (Myosotis scorpioides)
Yellow iris (Iris pseudacorus)
Emergent plants
Arrowhead (Sagittaria sagittifolia)
Branched burweed (Sparganium erectum)
Flowering rush (Butomus umbellatus)
Sweet flag (Acorus calamus)
Floating leaved plants
Amphibious bistort (Polygonum amphibium)
Broad leaved pondweed (Potamogeton natans)
Fringed water lily (Nymphoides peltata)
Water crowfoot (Ranunculus aquatilis)
Submerged plants
Curled pondweed (Potamogeton crispus)
Rigid hornwort (Ceratophyllum demersum)
Water milfoil (Myriophyllum spicatum)
Water starwort (Callitriche stagnalis)
The following plants provide good wildlife habitat, but are not suitable for small ponds. On medium sized ponds of 40-60 square metres, frequent clearance will be needed if the following species are used, in order to retain diversity.
Possible problem plants
Common reed (Phragmites australis)
Greater reedmace (Typha latifolia)
Mare’s-tail (Hippuris vulgaris)
Reed canary grass (Phalaris arundinacea)
Reed sweet-grass (Glyceria maxima)
Plants to be avoided
These plants should not be introduced, as they grow vigorously, excluding slower-growing species.
Australian stonecrop (Crassula helmsii)
Curly waterweed (Lagarosiphon major)
Parrot’s feather (Myriophyllum aquaticum)
Nuttall’s pondweed (Elodea nuttallii)
Water fern (Azolla filiculoides)
