Saving Hertfordshire's beautiful rare rivers
PUBLISHED: 11:18 16 July 2019
The county has a habitat so rare that the local Wildlife Trust has appointed a Living River Officer to help look after it. Sarah Perry dives into Herts' chalk rivers
A dash of orange and blue darts past, so fast you just see its form as it plunges into the water. The hunt was successful, the kingfisher emerges with a small fish in its beak. It perches on a low-hanging branch enjoying its meal. We're at the river Mimram, a small chalk river that rises from a spring in North Hertfordshire before joining the river Lee in Hertford.
What are chalk rivers?
The Mimram is one of only 200 chalk rivers worldwide, of which nearly 10 per cent can be found in Hertfordshire. Our chalk rivers come from the Chiltern Hills where rain water permeates layers of chalk to the aquifers below. From there the water emerges through fissures as springs. This water is a stable temperature, rich in minerals and pH-neutral.
Chalk streams are shallow and fast-flowing and their waters are crystal-clear. This creates the perfect conditions for a huge array of wildlife - from the smallest mayfly, dragonflies and other invertebrates to fish and birds such as kingfishers and herons as well as our fastest declining mammal, the water vole. A whole ecosystem depends on these special rivers.
What's the problem?
Hertfordshire's chalk streams are under pressure from the county's rising population and the associated increase in water usage. Up to 60 per cent of our domestic water comes directly from the chalk rivers' aquifers and more water usage means more abstraction. Add periods with little rain, like last summer and winter, and many rivers are facing severe pressures, and with them the wildlife that relies on them. Over-abstraction leads to reduced water flow which causes silt to build up.
Furthermore, our rivers suffer from pollution from urban and agricultural sources, invasive species, and past physical modifications such as weirs, dredging or straightening.
How can they be saved?
The task at hand is a huge one - no one single organisation can manage this alone. So Herts and Middlesex Wildlife Trust is working with farmers, local communities, river groups, the private sector and volunteers. Restoration projects across Hertfordshire include lowering weirs, removing scrub and trees that shade rivers and installing in-channel features to improve the habitats.
It's not only conservation organisations that can help, everyone can contribute. Because much of the water for our homes, workplaces and schools comes from the same aquifers that feed our chalk streams, we can make a direct impact by using less water. Every drop you save at home will be one more drop for wildlife.
Discover the rivers
If you'd like to learn more about our precious chalk streams, visit the Festival of Wildlife at Panshanger Park near Hertford this month. The free, family-friendly festival organised by Herts and Middlesex Wildlife Trust, in association with Herts Natural History Society and Tarmac, celebrates the rich diversity of wildlife on the site. Experience the fantastic river Mimram in the Chalk Stream Discovery Zone, go on a guided walk, and find out more about water voles and other wildlife at expert talks. Visitors can learn how to survey and identify invertebrates - grab a sweep net and see what you can find, or get to know local conservation charities. There's advice on bird watching and ringing, local artisans and craftspeople, and lots to keep the little ones busy in the Children's Activity Marquee.
Herts and Middlesex Wildlife Trust's Festival of Wildlife takes place on July 27-28 at Panshanger Park near Hertford. Find out more at hertswildlifetrust.org.uk