Part 2 of our follow up to WODC Water Day.
Sorry for the delay. We are still waiting for the details of the turbidity study presented at Water Day to be provided by the EA. We would like to see the rationale for laying the blame at the door of a geological fault which occurred some 60 million years ago. In the meantime, here is an interim observation that you should find interesting.
It seems to us that the geology has probably not really changed in the past 20 years whilst the river clearly (if that is not a terribly ironic word) has altered dramatically.
This was downstream of the road bridge at Crawley in the 90s. Maybe some of you remember it like this?
Look at that lovely clear water. We will grab another one right there next summer but for now, the scene below is now typical of most of the river around there, as many of you will know. The weed has gone and the water is murky. Gravel is covered in sediment.
Could it be more likely that the changes we have seen are something to do with something that has also changed in that time? The numbers of households in the valley has increased and so has and so has the quantity of sewage effluent and untreated sewage going to the Windrush.
Look around at the extra houses that have been built in places like Bourton on the Water and the other Windrush towns and villages and consider this. The population equivalent (population + factors like trade effluent) of Witney Sewage Works was 28,000 in 1995 and is now around 49,000.
The idea that this is a natural phenomenon that suddenly occurred seems very hard to believe and the evidence presented to back it up looks shaky to say the least. The full study will show just how conclusively those links were made when it arrives.
Then we found this. Presented in a bigger document for the Chiltern AONB. This slide seems to describe very accurately what has happened to the Windrush.
We know we are getting high plant nutrients in the form of phosphates from the sewage works and 'rich' additions from more untreated sewage spills than have been reported by Thames Water or discovered by the EA. WASP has uncovered them - more to come on this..
Could there be a connection?
Take a look at the logo on the bottom left of the slide.
However, if we are sceptical of the geological explanation and want to see the substance behind it, we have to do the same with this and will check it out see how the two compare on provenance and report back to you.
The full slide set we found is here and it was about agriculture's contribution, but the principle applies to whatever plant nutrient provider is delivering the goods and on the Windrush we have seen high levels at the sewage works. Let's keep an open mind, but also an enquiring one.
Plant food for thought - why was this not brought up at Water Day?