Ponds are an important biodiversity resource in the Irish landscape as they support a wide variety of plants and animals that live in or near freshwater habitats. They provide connectivity as they are important stepping stones and ‘refugia’ or ‘safe havens’ for native species, especially in intensively managed agricultural landscapes.
Preferably ponds should be excavated in wet areas, e.g. where wetland plant species are growing within your site. This indicates that the water table is high and almost certainly avoids the requirement to line the pond. In drier locations the pond will need to be lined.
Ponds should be sited in sunny but sheltered spots. The pond should be in the sun for most of the day; although if a very small pond, plants will be needed on the perimeter to provide light shade.
When selecting a location for your pond avoiding overhanging trees, if possible, as large amount of leaves will reduce the amount of oxygen in the water and will reduce the oxygen supply, which may affect the pond's inhabitants.
Building and Maintaining Ponds
When excavating a pond ensure that one side of the pond is deep to allow aquatic species refuge in very warm or cold spells. The other sides should be soft sloping or stepped to allow plants to colonise the edges, to provide access to the water to wildlife and to provide suitable breeding grounds for Common Frog. Steps allow different depths of water for different plant species. The shallowest step can be separated from the main pond by a water permeable barrier such as soil and planted with native species to create a wetland garden or Wet Grassland GS4 or Marsh GM1 area. Around your pond leave sufficient vegetation to provide cover for amphibians, escape routes for dragon and damsels flies and enough gaps to allow birds to come down to drink.
Where required, puddle clay can also be utilised to line ponds. Alternatively, liner can be purchased from local garden centres. It is important to maintain a minimum amount of water in your pond. During the summer months water may need to be added to your pond, especially if the pond is lined. Rain collected in a water butt is ideal as it will not contain any water treatment chemicals which are present in tap water.
During warm periods or where excessive nutrients have built up in the pond, it may become choked with green algae due to eutrophication. Barley straw (wrapped in mesh or hessian) can be added to the pond as this will assist in removing the algae as opposed to the use of chemicals. Introducing native oxygenating plants such as pondweeds also helps.
Maintenance operations in the pond, where necessary should be carried out in early autumn to avoid disturbing hibernating species. When vegetation and silt is removed, leave it on the bank to allow any trapped pond life to escape back into the water. Planting native aquatic plants in pots and putting them in the pond will help to control the rate of growth and the amount of maintenance required.
Avoid use of fertilisers, herbicides and pesticides close to water as runoff could prove harmful to aquatic life.
Wildlife will arrive and colonise your pond over time. Do not gather Common Frogs or frog spawn and bring it to your pond. This is against the law. In time, frogs will seek out a pond and spawn there once conditions are right for them.
Introducing ornamental fish is not a good idea as they eat a lot of tadpoles and insect larva.
If wetland plant species are present in the vicinity of the pond these will naturally recolonise the pond. This is the most environmentally friendly means of establishing vegetation in a pond.
In the absence of certified Irish provenance plant material for wetland and aquatic species on sale in Ireland, it is not recommended that aquatic plants are purchased, for example, in a garden centre. The most environmentally friendly means of establishing vegetation in a pond is through natural recolonisation or to acquire native wetland species from a suitable habitat in your local area. Remember, some sites are legally protected as they are located in designated conservation areas or contain protected species. It is not recommended to take plant material from these sites as a general rule. However, plant material may be gathered from these sites in consultation with the NPWS in exceptional circumstances e.g. mitigation and compensatory measures for a national road scheme. The location of designated protected areas in your locality can be found on the NPWS website.
Always notify the NPWS and acquire a license and/or written permission as required where translocation of plant material is proposed. Notify local NPWS staff and IFI prior to a translocation event, especially where the donor site contains protected aquatic species such as mammals, amphibians, fish or shellfish. In addition, ensure that permission is also acquired from the local landowner.
Non-designated remnants of wet woodland, bogs and marshes, ditches at the base of hedgerows, stream banks, ponds and lakes in your locality will have a diversity of common plant life. These sites are most suited for acquiring native plant material for your pond. Remember to acquire permission from the local landowner before entering any of these areas and avoid non-native invasive species in particular.
Chose a wide selection of native plants, as different types will support different species. Be careful when selecting aquatic species as some grow rapidly and will choke your pond especially if it is a small garden pond e.g. marginal species such as Common Reed and Bulrush. Suitable flowering species for planting along the edges of the pond are Water Speedwell, Water Plantain, Brooklime, Yellow Flag, Marsh Marigold, Branched Bur Reed and Fool’s Watercress.
Submerged species such as Spiked Water Milfoil, Fennel-leaved Pondweed and charaphytes will provide important refugia for flying insects such as dragonfly and damselfly larvae, and amphibians such as Common Frog and Smooth Newt. Free floating emergent species such as Amphibious Bistort, Broad-leaved Pondweed, Frogbit and White Water Lily will also enhance biodiversity and help keep the pond cool during warm weather because of their floating leaf bases.
Do not take excessive amounts of plant material from habitats in the wild as this may result in the loss of that plant from an area. Only a very small amount of plant material will be required for your pond as pond species generally grow quite rapidly and will colonise the margins of your pond. Make sure to collect the root base of the plant and transfer to soft sediment/wet soil in the recipient pond where it can establish. Ideally plants should be removed and translocated in the autumn once summer growth has finished. When transporting these species make sure to keep them moist in a watertight container so that they don’t dry out. Direct transfer from the donor site to the recipient site is recommended.
Always use hand tools. Do not mechanically disturb habitats or cause the release of soil/sediment in a watercourse from stream or river banks. Preferably, take plants from pond or lake margins (as opposed to river or stream banks), where plants are more widely distributed and disturbance impacts to the environment are not as great.
Remember to clean hand tools and containers for carrying plant material before and after use to avoid transfer of invasive species. Do not take plants from areas containing non-native, invasive species such as Japanese Knotweed, Himalayan Balsam, Nutall’s Pond Weed or Zebra Mussels. If in doubt, please check Invasive Species Ireland or the National Biodiversity Data Centre websites to identify these species. In addition, always be careful when working close to water and stay safe. Do not work alone close to open water and always wear a life jacket.