Natural Resources Wales explains why River Dee turned murky orange colour over past few days
Natural Resources Wales has explained why a stretch of the River Dee between Deeside and Cheshire turned a murky shade of orange over the past few days.
The change was first noticed on Thursday, 11th May, when residents around the Chester area reported the river appearing orange and cloudy.
Stunned by the sudden change in the River Dee, local residents turned to social media to post pictures of the usually clear, greenish-brown river now displaying a startlingly bright orange hue.
While changes in a river’s colour can occur due to a variety of factors, including natural sediment disturbance and run-off from nearby sites, the rapid and extensive shift in the River Dee’s appearance was cause for concern.
Posting on Twitter, @GreenGrounded reported the river’s turbidity, a measure of water clarity, leapt from 20 to a substantial 200 Nephelometric Turbidity Units.
@NatResWales @EnvAgency WHAT ON EARTH has happened to the River Dee in the last 30 hours? Yesterday it was clear (turbidity about 20) & greenish brown. Today it is incredibly murky (turbidity 200) & bright orange! Looks as if it’s full of clay. Pix from Eccleston Ferry, Chester. pic.twitter.com/SFNCgnEv5z
— Vertebrate (@GreenGrounded) May 12, 2023
While changes in a river’s colour can occasionally occur due to natural sediment disturbance or run-off from construction sites or farmlands, the speed and extent of the River Dee’s transformation have left many puzzled.
Some speculated it could be related to a pollution incident or sewage discharge, others said it was related to heavy rainfall.
@gfields1977 suggested that the murky water was caused by “torrential localised showers on Thursday night scrubbing the catchment.”
Heavy rainfall can stir up sediment in a river, leading to increased turbidity and a change in colour.
However, such a dramatic transformation as witnessed in the River Dee is relatively rare.
Something very odd had happened to the River Dee in Chester! Definitely not sewage though thankfully pic.twitter.com/fJhe0GAEiy
— Katie Lake (@KatieLake1918) May 13, 2023
A superb morning of “club racing” 16 4s & VIIIs timetrialing and then racing side by side for @nsr_uk practice on our own, self styled “Willy Wonka” River Dee! Quite the morning with the x5 senior VIIIs putting in some Ks before the internal regatta #supersaturday pic.twitter.com/c4zb5oTOez
— King’s School Rowing (@KSRCRowing) May 13, 2023
Natural Resources Wales (NRW) has said officers have been closely monitoring the situation.
David Powell Duty Manager for North Wales, confirmed that heavy localised rainfall was the cause of the river’s sudden shift in colour.
The news brings some relief to concerned locals, who had feared the change could indicate a pollution incident or some other environmental disruption.
David Powell, Duty Manager for North Wales said:
“Following reports of red, cloudy water in the River Dee in the Chester area on Saturday, we can confirm the discolouration was caused by heavy localised rainfall in various parts of the River Dee catchment on 11 May.
“NRW officers have been monitoring the plume.”
[Main photograph by Alan Fear]
