The River Bulbourne at Berkhamsted

Berkhamsted is fortunate to have a chalk stream running through the town centre. Historically the Bulbourne was rich with wild trout, the gravel bed forming an ideal hatching ground for trout eggs. Watercress thrived in its shallow spring-fed water and willows provided raw material for the local basket weaving industry.

The water flow of chalk streams is dependent on the height of the underground water table in the chalk bed rock. Historically this level was high-- requiring an overflow in the form of marshy flood meadows. This all changed when the grand Union Canal was built and began to pump water from the underground water table with pumps at Northchurch and Dudswell. Later still, as the town grew, the public utilities increased their take. Gradually the flood meadows dried out and the Bulbourne, like the other Chiltern Chalk streams, became a "low flow" river, often drying out completely during the summer months.

Rainfall from October -March would see a temporary return of water, but the combined abstraction of the Water Companies and the canal would reduce the water table to the no-flow state.

What might be regarded as the final insult to the river, was that as Berkhamsted grew surface water drainage was discharged into the river. These large surface water drainage pipes can be seen in the river banks of the town stretch at regular intervals along its length.

Apart from being an ugly unnatural feature these pipes bring in oil and silt from the roads. The silt settles on the gravel, making it unsuitable for fish hatching; oil floats on the surface, blocking the oxygen necessary for a healthy ecosystem.

In 1999 Berkhamsted Town Council decided on a River Bulbourne Restoration Project. They brought together all the river-interested groups, the Environment Agency, the Chilterns AONB, the Borough Council, and others. A 5-year plan was agreed with joint funding from the partners.
The first AIM was to increase the flow of water by narrowing the river channel; the increased flow would scour the gravel and keep it free from silt.
The second AIM was to reduce the heavy shading from the canopies of trees, mostly willows and alders that had been allowed to grow unmanaged since the basket industry died. If these trees were coppiced or pollarded, sunlight could reach the river plants on which a healthy ecosystem depends.

These two AIMS had been successfully completed by May 2007.

Most of the gravel bed can now be clearly seen as in the [picture below. The Chiltern AONB Chalk Stream Project has a plan to re-introduce trout as a school study.

Channel-narrowing had to include dealing with the artificial deep water lake created some years ago when the Borough Council excavated the riverside in the St. John's Well area. The pictures below show some stages in work of restoring the original watercourse with piles and bundles of faggots. And creating a refuge for waterfowl. During the drought of 2006, when the whole river and lake dried out, the refuge was the only part to retain its water.

The deep water of the lake has been filled with faggots and planted with native marsh plants. So in future in a summer drought like 2006 instead of bare mud there will be a natural marsh; the silted faggots will hold enough water to prevent drying out.

We also completed our second AIM by coppicing and pollarding all the riverside trees from Waitrose to Park Street. See picture below. This has been very successful in opening up the river to sunlight. There is now abundant vegetation growing in and around the river.

Last, but not least, the Bulbourne will benefit hugely when Thames Water is able to close down the New Ground pumping station at Cow Roast, Northchurch.
This was due to happen in 2005 but Thames ran into technical difficulties and had to start pumping again. When the Water Company has solved its problems we may have an end to "low-flows" and who knows, we might even see the wild trout again!

Author: Betty Patterson, February 2008