Precious Water

Here in Cambridge our water come from underground, mostly from the chalk under the Gog Magog Hills. This is a great resource as it acts as a giant reservoir, plus the water is filtered naturally by the chalk as it flows down into the aquifer. However, the same aquifer feeds streams that provide important habitat for wildlife. If the level drops too far then those streams can dry up - as they did in summer 2019. The flow in the River Cam was reduced to a trickle too for the same reason. It only takes one or two dry winters for this to happen. See this demo for how our water use affects the chalk streams.

Is climate change to blame?

Not entirely, though it definitely makes it worse. Climate change brings extreme weather of all kinds:

  • More heavy downpours . When rain comes in torrents, the ground cannot absorb it fast enough and it runs off into the rivers very quickly. We also get flash floods. Water that is not absorbed into the ground is wasted as far as the chalk is concerned.
  • Longer growing season. During the growing season most rain is used by plants – either in our gardens, on farmland or in the wild. The warmer weather means growing seasons are longer and the winter period when the aquifer fills up again is shorter
  • Hotter summers. When the weather is hot we use more water – to keep ourselves clean, to water the garden and to have fun. One medium sized paddling pool can double your family’s water use for the day.

What can we do?

The main thing is to use less water, both at home and in the garden. Here are some tips but there are links to more help on the Links page.

  • Fix dripping taps
  • Do not leave the tap running while washing vegetables or washing up - use a bowl
  • Get a water butt - plants prefer rainwater anyway
  • Take shorter showers

Chalk streams

Photograph: Yvonne Chamberlain © 2018
Source: the Waterlight Project

Ruth Hawksley (Wildlife Trust BCN) says: These habitats are very rare, our local equivalent of rainforests... It's their "special water" that makes chalk streams important - that water has been slowly filtered through the chalk so that by the time it emerges at the springs that start chalk streams, it is crystal clear, low in nutrients and pollutants, and at a fairly stable temperature .... All these conditions allow plants and invertebrates to thrive that you might not find in other places. These attract larger creatures such as kingfisher, otter, and water vole to create a diverse community.