Investigations into the Balcombe pollution incident that turned water in a stream bright green indicate that the cause was probably a green dye.
No harm to oxygen levels in the water, or to fish and wildlife or to drinking water has been detected, according to the Environment Agency.
The EA is conducting tests to establish what caused the green colouration and says “a number of potential activities and sources of pollution have been identified and eliminated”.
However, the agency says the source of the pollution still remains a mystery.
Meanwhile, Cuadrilla, which has been drilling a test borehole close to the stream, said the company was not responsible for the pollution.
It said: “We are aware of the green water and we are confident that it has nothing to do with Cuadrilla.
“The EA are aware and will be testing the water and enquiries about this should be directed to the EA.”
The EA has now said that the most common types of farm and sewage pollutants that can end up in water courses are not being indicated at the Balcombe stream.
On its website the agency says: “We followed the course of the stream and traced the pollution to a culvert under the railway line so we are now looking for the source upstream of this.
“Our field measurements have shown that there is no ammonia present in the stream and that dissolved oxygen levels are at 81 per cent.
“These levels are normal for this type of watercourse. The presence of ammonia is most commonly an indicator of sewage pollution, and low oxygen levels an indicator of organic pollution (eg sewage, milk, farmyard manures/slurry).
“We have found no evidence of an impact on invertebrate or fish populations.”
The agency is not equipped to measure levels of more complex chemicals and pollutants in the field so samples of stream water have been sent away for detailed analysis.
So far it says there is no indication of environmental harm and initial assessment suggests that the substance in the water was a green dye.
The EA was alerted to the incident by several callers who reported that a short section of the stream had turned bright green.
Officers visited the watercourse on Tuesday (October 1) with the police to make an initial assessment and to take samples.
Protesters and their camp, where they have been living since July to opppose Cuadrilla’s activities, are still present by the side of the B2036. although not in the same numbers as a week ago or as at the height of the protests.
After the first visit, the EA said the green substance posed no threat to the local water supply which comes from Barcombe some 15 miles downstream of the site.
The EA said: “We are continuing to actively monitor the situation but would encourage members of the public to report any subsequent pollution incidents on our incident hotline number 0800 807060.”
Since the incident was reported social media sites have attracted views about the cause of the green colouring including suggestions that it might be a dye called fluoroscein.
The pictures here were supplied by Natural Springs UK, a Dartmoor-based platform for promoting and preserving springs all around the UK.
Natural Springs UK is a registered charity which says its work is based upon the idea of connecting people back to what the earth provides, especially fresh water.