The poor state of our local rivers has had exposure in the media, but we need to move the conversation on to examine the detail of the causes and importantly to what solutions are being implemented to reverse this decline.

There are many Thames Water operated failing sewage treatment works in the Colne catchment including, Markyate into the River Ver,  Berkhamsted into the River Bulbourne, Chesham into the River Chess, Maple Lodge into the River Colne, Gerrards Cross and Amersham Balancing Tanks into the River Misbourne and Dagnall into the River Gade via groundwater. This is placing the environment of the whole Colne Catchment under significant strain, the impact of this can be witnessed first-hand with a visit to a number of locations in the region, most notably the River Colne at Harefield or the River Misbourne. This is unacceptable. A dramatic and radical approach is required to create a robust solution that deals with current and emerging challenges, including micro plastics, pharmaceuticals, “forever” chemicals and the need for reliable clean water supplies. We suggest early discussions with Thames Water to create a plan and explore what commitments are required.

There are many members of the public, businesses, recreational groups, educational institutions and farmers directly impacted by this pollution and they require immediate attention and compensation. Prompt action by Thames Water, Environment Agency and Government on these matters is required.

All of the rivers mentioned above are chalk streams, globally rare habitats and deserve respect and protection. Over the last 20 years we have seen a marked decline in the quality of sewage processing, this year is heading to be the worst yet.

The best way to address this is to stop the ingress of groundwater coming into the sewage treatment works that is overloading their capacity.

It will cost a lot of money to improve treatment of sewage and address decades of under-investment. In short, someone has to pay for this whether shareholders, government or water users but there must be the political will to act to ensure this long overdue investment happens.

The Detail

Sewage Pollution of the River Colne in Harefield Makes the National News 05/04/24

Sewage Pollution of the River Misbourne: its cause and effect 29/02/24

The River Colne - A Toxic Soup of Chemicals ? 20/04/23

A list of main the pollution sources for the catchment (Thames assets) and where they discharge to. 

Markyate to Ver

Caddington to Groundwater – likely into Ver via ground

Dagnall to Groundwater – likely into Gade via ground

Codicote to Groundwater – (probably too far away to affect us)

Trumps Green to Bullbourne

Fulmer Drive (Howards Wood Drive) to Alderbourne and eventually to Colne

Berkhamstead to Canal and indirectly to Bullbourne via overflows from canal

Blackbirds Farm to Colne – Normally just final treated effluent but storm can be diverted to river if required or as necessary - no EDM

Chesham to Chess

Gerrards Cross to Misbourne

Amersham balancing tanks to Misbourne 

Maple Lodge final effluent  to Canal/colne (same entity)

Maple Lodge Storm to Colne (Mill end loop) 

Iver North into Colne Brook

Numerous large attenuation tanks in Watford area (no EDM’s but they often overflow to Colne)

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