Tavy pollution?

The Somerset Frome and Dorset Stour and westwards
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pete thorn
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Tavy pollution?

Post by pete thorn » Thu Sep 27, 2018 3:32 pm

I had a very constructive meeting with people at South West Water about pollution, particularly on the Tavy and Walkham. There is a long anecdotal history of paddlers becoming ill after paddling, particularly below Tavistock. Grey smelly discharges have been seen there, even at low water levels, though this seems to have been less in recent years? Any information on last season would be helpful if you had any illness after paddling. SWW have also noted that there are other potential sources of pollution such as agricultural pollution, septic tanks etc.
SWW have a wastewater catchment area which includes a lot of houses where rainfall run-off and sewage is not separated. In times of heavy rainfall they have storage tanks to catch storm water (wastewater and runoff) flows, which can be processed later. These systems can get overwhelmed if there is continuous rain or when a band of rain is followed closely by another. Then storm water has to be discharged into the river in line with permits from the Environment Agency. This may not be a problem in high flows as the dilution ratio is high, but certainly is for us if it continues after the river has dropped. Another factor might be the need for cleaning of the main sewers, which can become restricted by all sorts of debris and road dirt, including fats etc. The Tavistock sewer is scheduled for cleaning and this can take up to six weeks. The Horrabridge works are having a big new storm water holding tank built but that is some years away.
While storm discharges can legitimately occur when a river is in low flow because of spates in other catchments, Officers at SWW are keen to prevent any incorrect storm discharges at times of low water. They welcome reporting from paddlers if you see what seems to be untreated wastewater being discharged at normal or low flow river levels. Any such report has to be reported to the EA by SWW with details of any action taken. This could help SWW to make earlier interventions, reduce pollution and help the EA and SWW with the identification of misconnections / other sources of problems. The link to the SWW website is under ‘Suspect a Pollution’ and can be accessed here https://www.southwestwater.co.uk/water- ... pollution/
Storm water discharges happen hydraulically, according to flow and height levels. If there is something wrong with the system SWW want to know about it. To that end they are busy fitting Event and Duration Monitors which record all these activities as part of a Storm Overflow Assessment Framework. All the EDM data is submitted to the EA annually and used to identify if there problems and/or if there is a need to reduce the frequency of storm water discharges by providing more storage or separating storm water from the wastewater collection system. This EDM data is in the public domain.
We discussed the possibility of real time data on storm water discharges to be publicly available, maybe linked to EA river level data. They have agreed to look into this as it would give better information on discharges.
There was a genuine desire to work with us on this to create something similar to Beach Live which seems to work well where discharges happen on beaches, although it may be that the new monitoring will drive significant improvements in any event, as the main issue for paddlers would be incorrectly operating storm discharges. I have a meeting with the SWW Conservation, Access and Recreation Forum in mid October so will keep this issue on their agenda.
Pete Thorn

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PeterG
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Re: Tavy pollution?

Post by PeterG » Fri Oct 12, 2018 3:23 pm

Southern Waters new system of +/- real time reporting is good, although the ones I'm signed up to are into the sea. I was ill on the Tavy some years ago and logged it with the EA at the time

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