More news...

Feb 4, 2019
Category: General
Posted by: Kathryn

Flow monitoring on the upper and lower Chess reveals the good, the bad and the beautiful.

Jul 6, 2018
Category: Drought
Posted by: Kathryn

With this hot weather our water use goes up; this leaves less water available for the Chess.

May 3, 2018
Category: Abstraction
Posted by: Kathryn

With an ever-growing demand for drinking water and increasingly extreme weather events, how do we get the water we need without causing even more harm to our rivers?

May 2, 2018
Category: Drought
Posted by: Kathryn

Our riverfly monitors are back out in the centre of Chesham checking for life in the Chess now that flow has returned.

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A Winter's Day on The Chess

Feb 4, 2019

Category: General
Posted by: Kathryn

We were out today monitoring riverfly at Scotsbridge Mill, Rickmansworth, with a new volunteer and attempting to flow monitor at Duck Alley in Chesham. Between these two locations you see the good, the bad and the beautiful on the River Chess. At Scotsbridge there was a reasonable flow of clear water. We had a good score of riverfly with 6 out of 8 target groups present and in good numbers. We also saw evidence of breeding brown trout; we think the recent cold snap has triggered breeding activity. The female trout builds a nest “redd” using her tail to flick up loose gravel on the riverbed to create a depression. She lays her eggs in the redd where attending males compete to fertilise them. For the eggs to thrive they need to be in contact with oxygenated water; if they get covered in sediment this does not happen and the eggs fail to hatch.

View a video of trout spawning in the Chess

A trout redd in the river channel

 

Here you can see a trout redd (nest). The lighter patch of gravel is the material excavated by the female trout. There were 7 or 8 of these redds in a 30m stretch

 


Leaving Scotsbridge we ventured upstream to monitor flow at Duck Alley in Chesham. There was water flowing from the Vale Brook tributary, but nothing flowing in the main river. Flow was so slow and shallow it was too small to measure. It was also quite discoloured. Where it "flows" through the Meades Water Gardens you see great banks of black silt, which have accumulated from the years of urban and agricultural runoff. Without strong, consistent, clean natural spring and groundwater flow this channel will remain silty and full of pollutants. Very depressing. So how do we improve flow? Well, we have to hope for wetter winters and reduce or stop abstraction for domestic supply. This means finding alternative sources of water, here we need more reservoirs to capture rainfall in times of plenty.

On the bright side, below Lords Mill we see clean, reliable flow from what we believe is an abandoned industrial water supply; the "mystery pipe". This pumps millions of litres of clean water into what would be a dry channel, keeping the river flowing below Lords Mill. Between Lords Mill and Canons Mill, brown trout have been at work. For the fourth year we see evidence of breeding activity and redd building, similar to that seen earlier in the day at Scotsbridge. Here the water is clear and the gravel clean due to the supply from the "mystery pipe". We hope they are successful in what can only be described as a dribble of water.

Artesian borehole

Above: flow from an old aretsian well by Chesham Moor

Crossing Chesham Moor we saw further encouragement. An abandoned artesian well, from the days of watercress production pumps out crystal clear spring water. The surrounding riverbed was full of healthy river-weed and clean gravels. This is what we should be seeing along the whole of the Chess; this is what we aspire to. This is what all chalk streams should look like - an oasis of wonderful habitat and so close to the centre of Chesham. One day we hope to see this in Duck Alley and Water Lane in the centre of Chesham. It was once like this and not too many years ago; sad to see how quickly it has declined.