Dew Ponds
Introduction
Something we all have in common is that we need water. Our animal friends are no different. Urban development, habitat loss, and climate change has made water harder to come by in many places so this page covers a few options for helping them out.
What Is A Dew Pond?
"A dew pond is an artificial pond usually sited on the top of a hill, intended for watering livestock. Dew ponds are used in areas where a natural supply of surface water may not be readily available. The name dew pond (sometimes cloud pond or mist pond) is first found in the Journal of the Royal Agricultural Society in 1865. Despite the name, their primary source of water is believed to be rainfall rather than dew or mist." - WikiWand: Dew_pond
"They are usually shallow, saucer-shaped and lined with puddled clay, chalk or marl on an insulating straw layer over a bottom layer of chalk or lime. To deter earthworms from their natural tendency of burrowing upwards, which in a short while would make the clay lining porous, a layer of soot would be incorporated or lime mixed with the clay. The clay is usually covered with straw to prevent cracking by the sun and a final layer of chalk rubble or broken stone to protect the lining from the hoofs of sheep or cattle. To retain more of the rainfall, the clay layer could be extended across the catchment area of the pond. If the pond's temperature is kept low, evaporation (a major water loss) may be significantly reduced, thus maintaining the collected rainwater. According to researcher Edward Martin, this may be attained by building the pond in a hollow, where cool air is likely to gather, or by keeping the surrounding grass long to enhance heat radiation. As the water level in the basin falls, a well of cool, moist air tends to form over the surface, restricting evaporation." - WikiWand: Dew_pond
https://www.countrylife.co.uk/property/guides-advice/dew-ponds-to-the-rescue-36183 This page includes suggestions about how these work, where they have been found and in what estimated quanities. They used historic descriptions of builder team sizes, working seasons, methods and tools, including warnings about what types of weather should be avoided during the construction period. "Some people say an overhanging tree will help a pond a lot and I can believe that because, if you go out walking when the mist on the downs is extremely thick, you will find trees dripping with moisture.’"
Life Expectancy
Some old dew pools in Britain are suspected to date back to the medieval period. Traditionally constructed pools can easily last for centuries, but more recent dew pools made from cement cracked fairly quickly.
Con: These are less suited for low-lying areas as they can lose depth and effectiveness if filled with debris or silt.
Solution: Avoid planting trees (especially species like willow) near these to protect the layers, and to reduce the amount of litter that can fall in.
Materials:
Bottom Layer: Chalk or lime to deter worms.
Additives: A layer of soot would be incorporated, or lime mixed with the clay layer.
Insulation Layer: straw or hay
Surface Layer: Chalk, clay, or marl
Protective Rock Layer (Optional?): rocks or rubble to protect the chalk layer from the hooves of large animals.
Fuel Types: Water Cycle - scientists don't appear to have determined how exactly these refill, other than dew probably not being the source. Explanations range from rainfall to groundwater seeping upward, but these hilltop ponds have been found to contain water during droughts even when lowland pools have run dry.
In the 8:37 minute video below a man talks about how his local dew pools have been filled in over the years, talks about the history of the village and it's pools, then demonstrates how he has helped to clear them out. Another person clearing out a different dew pond reminded watchers to leave any pond plants by the water side for at least one night or more to give small animals a chance to escape back to their homes before composting or otherwise disposing of the remains.
One suggestion that came up while researching these is to make sure that the pond lies in a depression. Cool air settles, creating a cool barrier over the water surface which both discourages evaporation, and may even help refill the ponds.
Benefits of Dew Ponds
Biodiversity
Provides high-elevation water for livestock, wildlife, and it is believed that the nursery rhyme about Jack and Hill may have referred to one of these, rather than an actual well which relies on ground water to recharge. Restoration of the ancient pools can bring back vital habitat for endangered newts.
Fresh Water is in Short Supply on the Hill Tops of the Yorkshire Wolds "A dew pond offers an oasis for wildlife in this otherwise dry, chalk landscape. Scattered across the rolling hills, these ponds provide a vital source of water for a wide range of wildlife."
Impressive Durability
These are also super durable with Sir Gilbert White reporting that in 400 years he'd only found one example of leakage in one of these ponds and that was caused by roots of a tree pushing up through the lining.
Resources
Design & Construction
Historic Account of Construction Method
"A method of constructing the base layer using chalk puddle was described in The Field 14 December 1907. A Sussex farmer born in 1850 tells how he and his forefathers made dew ponds:
The requisite hole having been excavated, the chalk was laid down layer by layer, while a team of oxen harnessed to a heavy broad-wheeled cart was drawn round and round the cup shaped hole to grind the chalk to powder. Water was then thrown over the latter as work progressed, and after nearly a day of this process, the resultant mass of puddled chalk, which had been reduced to the consistency of thick cream, was smoothed out with the back of a shovel from the centre, the surface being left at last as smooth and even as a sheet of glass. A few days later, in the absence of frost or heavy rain, the chalk had become as hard as cement, and would stand for years without letting water through. This old method of making dew ponds seems to have died out when the oxen disappeared from the Sussex hills, but it is evident that the older ponds, many of which have stood for scores of years practically without repair, are still more watertight than most modern ones in which Portland cement has been employed.
The initial supply of water after construction has to be provided by the builders, using artificial means. A preferred method was to arrange to finish the excavation in winter, so that any fallen snow could be collected and heaped into the centre of the pond to await melting." - https://www.wikiwand.com/en/Dew_pond
Diagrams of Layers
Organizations
North America
USA
Water for Wildlife "is a conservation organization designed to benefit our nation’s wildlife. Our initial emphasis focused on plains game preservation and management through the development of supplemental water resources in selected areas where both the habitat and wildlife are being impaired by lack of water, a vital natural resource. We have now invested in over 500 water projects in twelve western states. These crucial water sources sustain both wild game and non-game animals including songbirds, raptors, waterfowl, fish, and many more. Our charitable goals are to create awareness of increased pressure on water resources necessary for the continued sustenance of wildlife and to increase the availability of water for all wildlife in remote and arid regions of our country. The Benefits Wildlife rely on their habitat for water, feed, and cover. As these resources become increasingly scarce, our projects support the continued viability of wildlife under these conditions. We work with state and federal wildlife and land management officials and other conservation organizations to identify the need for projects, located primarily on public land."
Grants & Funding
North America
USA
Water for Wildlife: Grant Application "The Water for Wildlife® Foundation is committed to playing a pivotal role in the conservation of wildlife through the development of supplemental water/habitat resources. WFWF helps bridge the gaps between agencies and other partners to implement projects. We provide grants each year for the construction of water/habitat developments for wildlife. Water for Wildlife® project applications should show at least a 1:1 cost share match for consideration. Water projects are ranked and prioritized for funding based on benefits to area wildlife, distances to perennial water sources, cost share funding and partners identified, cost effectiveness, public benefit, and completeness of application submitted. Funding levels vary from project to project, but typically range from $1,000 – $10,000. The Foundation is encouraging your agency or conservation organization to partner with us to support our efforts of making water/habitat as accessible to wildlife as possible."