Just off the coast of South Ayrshire, the sea appeared to boil in an unexplained incident on Sunday.
The Scottish Environment Protection Agency (SEPA) and Scottish Water were notified of the strange sight south of Girvan near Lendalfoot.
Paul Young captured images of the rippling water which he said was “pretty discoloured”.
After fears that it may be a ruptured sewage pipe, Scottish Water confirmed it had no issues reported on its network in the area.
The utility said it had no pipework in the area.
But on Monday, SEPA revealed the bubbling liquid came from a nearby landfill.
The environmental regulator said it was rainwater that had mixed with waste in the Straid Farm Landfill and was released as part of a “routine permitted discharge”.
The liquid, known as leachate, must be sampled and tested to ensure it meets “strict quality limits”.
SEPA said it would monitor the situation to make sure the operator complied with their permit.
The eruption follows several days of torrential rain that saw flooding across parts of the country.
A spokesperson for SEPA said: “SEPA is aware of reports of a visible upwelling off the coast at Lendalfoot, South Ayrshire, on Sunday, October 32. This is a routine permitted discharge of treated landfill leachate from Straid Farm Landfill.
“Leachate is rainwater which has come in to contact with waste within a landfill. It is collected within lined containment cells and then treated prior to discharge to the environment.
“In advance of discharging, the operator is required to undertake sampling to ensure it meets the strict quality limits outlined in their SEPA issued Pollution Prevention and Control (PPC) Permit.
“These limits are set on a discharge specific basis to ensure no adverse impact on the receiving water body.
“Given the heavy and sustained rainfall over the last couple of weeks there has been an increased volume of leachate needing to be treated and discharged. This will have resulted in a prolonged discharge and more noticeable visual impact than normal.
“SEPA will continue to monitor compliance with the operator’s permit.”
A Scottish Water spokesperson said: “We are not aware of any reported issues on our sewer network in this postcode area. Scottish Water has no sewers or infrastructure near or in Lendalfoot, where properties a served by septic tanks.”
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