Chalk Rivers and Farm Advisory

The River Mimram is a chalk stream, globally rare, being one of only 260 in the world.  Thanks to funding from the Environment Agency, we are excited to be working in collaboration with and supporting landholders, communities, stakeholders, to improve the river’s ecological health. Our dedicated Chalk Stream and Farm Advisory Officer, Heidi Mansell, will lead this work and the delivery of the Catchment Based Approach Chalk Stream Strategy

The River Mimram flows through the heart of Hertfordshire, beginning its journey near the village of Whitwell and meandering gently through the countryside, passing through several villages and towns before joining the River Lea near Hertford. The river and its surrounding catchment are more than just natural features and vital for our local wildlife; they are an integral part of the local community's identity and heritage. Villages along the river, such as Welwyn and Tewin, celebrate the Mimram through various festivals and events, fostering a deep connection between residents and their natural surroundings.

We are considering a catchment-wide approach to improving the state of the river, considering the entire area of land (the catchment) that drains into the river. This holistic approach will look at the river’s whole ‘supply area’, including rainwater, groundwater, and any other water sources. This is important because specific issues faced locally such as pollution, sediment, siltation, and invasive species often start in the wider catchment area and those who affect or are affected by the catchment should be involved in finding the solutions to these problems.  Different groups and stakeholders—farmers, local communities, businesses, environmental groups, local authorities, and government agencies—have been coming together for a number of years to try to improve the River Mimram and we now aim to consolidate on this work and make further progress in the coming years. The River Mimram catchment plan can be seen here -  https://www.riverleacatchment.org.uk/index.php/river-mimram-home

Heidi is supporting landholders to achieve improvements to flow, water quality and habitats within the catchment with the creation and delivery of action plans and ongoing monitoring. Particular species that we want to see thrive include Water Voles, Kingfishers, Brown Trout, Water Crowfoot, and invertebrates such as the Beautiful Demoiselle, Yellow Sally Stonefly and Yellow Dun Mayfly. All these species are indicators of healthy chalk streams. Across the wider landscape, we are aiming to increase the numbers of declining bird species such as Yellowhammers, Lapwing and Grey partridge. All of these are priority species within the emerging Hertfordshire Nature Recovery Strategy.

There will be opportunities for you to get involved with this project, as it develops. If you live or work within the River Mimram catchment and would like to get involved or find out more, then please contact Heidi Mansell at Heidi.mansell@hmwt.org