South East Rivers Trust (& the Wandle Trust)

Hogsmill: Assisting nature and being assisted by nature

Hogsmill Planting and Wooded Debris Fixing

Last Wednesday saw the Trust accompanied by the great volunteer help of Epsom and Ewell’s  Countryside Team return to the site of the weir removals that took place last August in the headwaters of the river in the Hogsmill Local Nature Reserve. The primary task was to kick start the establishment of the bank side vegetation which is required to encourage a complex root structure to help to stabilise the bioengineered banks. Planting took place towards the end of last years growing season and subsequently did not have long to settle in before winter took hold. This time we would give them the whole growing season to take hold. 

Semi-mature iris, hemp agrimony, purple loosestrife, meadow sweet, brook lime and a few bur reed, all purchased from a reputable supplier, were planted into the banks and marginal areas. In addition to these, translocated sedge taken from elsewhere nearby on the river were also introduced.  We undertook the planting at both the former weir sites. We now need a bit of sun and a bit of rain to encourage good growth, fingers crossed.

Kitted up and ready to plant.
The banks receiving a second coat of plants.
A well deserved rest.

Now that we had helped nature, we now took advantage of an offering that nature gave in return. During the winds and rain in the winter a large branch had been washed down the river and become wedged in a normally straight channel against a stone wall on the right bank. With more high flows more wooded debris collected on the branch, consolidating and stabilising the raft further. As the high flows continued the river carved out a meander into the natural left bank. This has produced a deep sinuous run with adjacent complex cover.  In the slack water created behind the structure siltation has started to accumulate which has quickly become populated by various marginal plants. This type of habitat is severely lacking in the upper reaches of the Hogsmill. Keen to take advantage of this, the Environment Agency where approached by the Trust seeking permission to formalise and fix the structure into place. With flood consideration given, consent to go ahead was granted.

With help from Nigel, the branches that would potentially catch further debris where removed both above and below the water line. Untreated chestnut posts were driven into the river bed either side of the structure and fencing wire passed repeatedly over the structure from post to post and secured with staples. The wire was then tensioned and structure fixed by driving the posts down further.

Before work..
and after, clear of debris snagging branches.


and after.

This is a great example to show that simple, quick and cheap techniques can sometimes be used to great effect.

Once again a big thanks goes to the kind help of the Epsom and Ewell’s Countryside Team volunteers as well as Stewart Cocker and Lindsay Coomber at Epsom and Ewell Borough Council for offering and arranging their time and energy.