A pond can be a wonderful addition to any garden, but especially to an allotment because it helps to increase the population of frogs and so decrease the population of slugs and other pests. It can also be a thing of beauty, bright with flowers, alive with bathing birds, seething with tiny organisms, some microscopic, some visible to the native eye.
Anyone, adult or child, who has ‘pond-dipped’ to explore life in the water will appreciate how exciting it is to have your very own pond. Across the country though, ponds are all too rare, often filled in on farms and on village greens, so an allotment pond is also making a contribution to preserving nature.
Digging a pond needs a bit of planning. Ideally, whatever its area, the pond should have one point which is about 70cm deep so that frogs and other creatures can shelter in deep water over the winter, away from the ice. It also needs at least one side to be shelving gently so that there is a route which the froglets can use to leave the pond and where birds can bathe. The other sides though can have a steep slope into the water, and you might want to use the earth you dig out to make a flowery hillock or a rock feature as a backdrop to one or more of those sides. As you dig, you can also create a shelf for water plants along the deep sides.
You need a good pond-liner (there is an excellent stock at pondkeeper.co.uk, and you can visit them in Stockton) and you should either invest in a felt layer to protect the underside or find an old carpet which will do the job just as well. Our pond has a felt layer over the top of the liner as well, which protects it from the UV in the sunlight, and also encourages plants to root in the bottom in a natural way (the alternative is to grow water plants in containers, which can look a bit artificial).
You will need plants like Hornwort or Pond Weed to oxygenate the water (most ponds tend to get overwhelmed with such plants, so you can certainly scrounge some from other pond owners as they pull theirs out), and there are a whole range of flowering plants available (you do need to think about the depth each plant prefers though; see https://www.rootsplants.co.uk/collections/all-pond-plants).
A new pond is likely to have trouble with the alga called blanket weed and you will probably have to pull it out regularly, but the water will settle down before long and the problem should disappear. It is best not to top up your pond with tap water, which encourages it, but in a dry summer you will probably have to. So there is a little maintenance involved, but the rewards are great!