Monday, 6 May 2013

River Gardening

One of the legacies of 250 years of pollution in the Irwell is the lack of complex plant structure in the river channel. Apart from the rocky headwaters, the water in most of the river has been too toxic to allow it to grow. However as we all know - things are changing.
Phosphate output from sewage works used to be abnormally high, which had the effect of covering the river bed in a thick layer of life clogging algae smothering anything which tried to grow, and in the lower river,  a form of ribbon weed had established itself - neither of which support large amounts of river life.

However - in 2009 United Utilities started to install ammonia and phosphate removal facilities at their waste water treatment works. The effect of this is much better water quality, and previously unrecorded species of aquatic plants are now beginning to appear in the lower river.
We are now - for the first time ever beginning to find the occasional stand of starwort and ranunculus (water crowsfoot) - these more complex plants offer great spawning material for fish, provide cover for fry, provide habitat to support huge numbers of aquatic invertebrates (fish food) and provide shading and cover for both coarse fish and trout.

All in all - a very desirable thing to have in our river.

Sadly - the re-colonisation of these plants is a long and slow process - and though the sight of a couple of stands of these plants below the footbridge at Kersal Dale is a positive indicator of things to come - we have long thought that these plants need a little encouragement to speed up their re-colonisation of the river.

Our original intention was to speed this re-colonisation process during the summer of 2013 by transplanting small root balls of both speicies from up river but the Environment  Agency are undertaking significant flood defence upgrades in the lower river this summer, involving lots of earth moving and heavy machinery in the river - so we have decided to delay this work until 2014.

The EA flood defence team - who wont allow us to make any in-channel improvements or plant river side trees to provide shading (which would be a great improvement fishing wise - are allowing us to transplant plants from upstream, and have offered to work with us next summer - which will be a great assistance.

So - with this in mind - when i was invited over to the River Don in Sheffield (another post industrial river which suffers many similar issues to the Irwell)  by Paul Gaskell of the Wild Trout Trust, and the guys from S.P.R.I.T.E. to take part in a rannunculus transplanting session I jumped at the opportunity.

Armed with my passport so i could cross the border, and some barmcakes so that I'd have something to eat when i got there - I took a trip to Yorkshire - the darkside of the Pennines.

The lads from S.P.R.I.T.E. had already transplanted some root balls of Ranunculus using ladies stockings to hold their balls together - this had me worried - but was apparently quite an effective method of protecting their assets- but to my relief on this occaision they were going to use hessian sacking to do the job - a but coarse - but as hessian quickly rots down in water - a much more environmentally friendly way of doing the job.

Take a look at these pictures of the mornings work

Transporting the lifted plants
A pool on the Don - not an aquatic plant in sight

work in progress

And how it looked after an hours work - these three foot long stands will be 20ft+ by the end of the summer, and will be covered in beautiful white flowers every spring.

Many thanks for a great day on your river - it looking good.
It will be a great project to replicate on the Irwell