Messy is better

Could a small boat, a chainsaw, and a hand winch be enough to bring a river back to life?  Possibly, in some cases.  An example comes from the River Bure, a short river, only about 50 long, flowing through Norfolk in northeastern England.  It joins the River Yare at Great Yarmouth just before reaching the North Sea.

A little north of the city of Norwich, the river passes through the Blickling Estate, a large country house and grounds managed by England's National Trust since the 1940s.  In the past, the river had been dredged and meanders blocked off to accommodate several nearby mills using the water power.  Trees that might fall into the river were regularly cleared away.  A visitor to the Estate might see an attractive country steam (below), but, in fact, the channelizing and debris clearing had seriously undermined its vitality.   

© D. Brady.  The National Trust

These measures, it appears, had caused the flow of water to slow down.  As it did so, silt, normally carried farther downstream, fell out and gradually covered over the gravel in the river bed.  Over time this process eliminated many of the spawning grounds for the local brown trout.  Eventually local fishermen and National Trust staff realized something needed to be done to improve the river's ability to support the fish and other plant and animal life.
 
In 2008 and 2010 the two groups undertook to recreate something like natural stream conditions.  This turned out to be fairly easy.  They carefully picked out trees that looked like they were about to fall into the river on their own, cut them, and let them fall into the river, branches, leaves and all.  In a few cases, they needed the hand winch to drag them into the water.

The result has been impressive.  As water squeezed its way around and through the debris, it accelerated and, in doing so, began to wash the silt off of the gravel.  With this, the trout began to return to spawn; the fishermen have recorded their increased numbers.  Some of the silt has been displaced out to the river banks where it has allowed new plants to take root.

© D. Brady.  The National Trust

The result (here) may be a messier looking river, but it appears to be much healthier.  And the lesson has been picked up by environmental agencies in the area; they are now much more likely to let trees that fall into streams just stay there.