Author: Nick Hale, Project Officer
And so 3 weirs fell!
Gatehouse, Weir 1
New Lodge, Weir 2
and Dairyhouse, Weir 3
Watch the video of their removal here:
A total of approximately 250 tonnes of concrete and steel was removed from the river.
Removing the three weirs has unimpounded over 1 km of channel. By reconnecting these previously isolated sections of river, just over 3 km of this part of the Lesser Teise is now fully passable for fish!
Increased flow velocity and diversity has already seen the return of natural processes such as erosion and deposition. The mix of deeper and shallower areas will create a range of habitat niches for invertebrates and fish etc.
Directly upstream of the former weirs, the flows have begun to rework the river bed and gravel berms until its natural gradient is restored (as before the weirs were introduced). A previously drowned-out ‘in channel’ meander sequence has exposed gravel riffles, berms and mid channel bars.
These gravels will be continually reworked in a downstream direction, being replaced by new material from upstream. The well-oxygenated gravel riffles will become ideal spawning habitat for both salmonid and coarse fish like brown trout and chub.
A number fish were identified during the works with species including brown trout, minnow, bullhead, stone loach, gudgeon, dace, roach, perch, pike, brook lamprey and barbel.
This stretch of historically dredged river is typically characterised by steep/vertical banks with little or no marginal habitat. This project has exposed an abundance of berms and marginal features that given time will be transformed into a diverse marginal habitat.
Removing the weirs has eliminated the landowners’ responsibility for the upkeep of the structures and saved costs on the twice a year maintenance visits from the EA to maintain the signage and clear blockages in the channel.
We will be monitoring the river over the next few years to record how the project develops. It will be interesting to see how the higher flows over the winter months rework all the gravels.
In the spring we will sow some native marginal plant seed mix on the lower banks of our structures and take some more photos for the next blog.
A BIG thanks to must go to the landowners, Ian Johnstone and the Kent High Weald Partnership and the Environment Agency for all their help!