All sorts of water fly spend the very large majority of their lives living on a stream bed as larvae called nymphs. These are the species we are worried about at the moment as a burst water main upstream pours sediment-laden water into the Lambrok for the third day.

Most water fly larvae, at some stage of their development, have gills; fine sediment in the water will choke gills so that the larvae cannot breathe. This is the time of year when the larvae of many species hatch into their brief adult lives, mate and lay eggs in the water which then sink to the streambed. If the sediment is settling and covers the eggs it will suffocate them. It is difficult to think of a worse time of year for this to have happened.

Yesterday the Environment Agency asked Wessex Water to reduce the water pressure so we hope there will be less sediment today than there was yesterday and we have, at least, been assured that the water is not chlorinated.

We don’t know when the leak began. We have been told that there was sediment in the Lambrok on Saturday afternoon. On Sunday morning, when a member of FoSCP followed the stream down from Southwick to find the source of the trouble, there was a Wessex Water sign apologising for the inconvenience. If Wessex Water already knew about the leak and knew the water was running into the Lambrok upstream of the park, why weren’t FoSCP or Wiltshire Countryside Team told about it? Why did it take the intervention of the Environment Agency before any action was taken to protect our stream.

Once again we have to ask Wiltshire Council why Southwick Country Park’s biodiversity does not have the statutory protection of Local Nature Reserve status. Wessex Water will be aware of all the Local Nature Reserves in any area in which it is operating and its response to them will be guided by policy and protocol.

Let’s hope for minimal damage to our stream.

Sediment in the Lambrok

Header picture by Suzanne Humphries; footer picture by DKG; others as attributed

Update (Monday 10.30am)

Today, the condition of the Lambrok is worse despite Wessex Water’s assurance they had turned the water pressure down. At the site of the burst pipe, the water is roaring like a waterfall; the volume has increased and it is flowing faster. We have reported all this to the Environment Agency; the person we spoke to seemed to think that the leak began on Friday.

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