Mine water could be the cause of Whitehaven Harbour mysteriously turning orange, harbour bosses said.
Whitehaven Harbour Commissioners is spearheading an investigation into the cause of the colour change and have called the situation frustrating.
The water first changed colour to a rusty brown back in late November, which led the Environment Agency to test the water.
An agency spokesman said: “Analysis of water samples from Whitehaven Harbour found no evidence of sewage pollution. The results did show some increased metals in the water, and we are actively investigating this further to determine the potential source.”
According to the harbour commissioners, the polluted water is entering the central harbour area via a culvert in Queen’s Dock and has spread to wider parts of the water.
John Baker, CEO of Whitehaven Harbour Commissioners said: “It seemed to clear up over the Christmas period but at the start of January it discoloured again and it is now worse than ever before.
“The Environment Agency have said there’s nothing alarming in the water, but it could possibly be mine water or connected to mining. Obviously there’s been a lot of mining around Whitehaven in the past so it could be something we do some exploring into to see what might be causing it.
“The real challenge at the moment is to find the root of the pollution and find a solution. It doesn’t look great and we’re very frustrated because we’re the ones at the receiving end of it. It’s directly affecting our business.
“It’s an intermittent colour change so there’s no set pattern. It’s a bit of a mystery really, but at the moment from the naked eye it looks worse now than it was pre-Christmas.
“It’s very frustrating for people who have boats sat in the marina and we’re pretty angry about it because somewhere along the line pollution is coming into our harbour and we need Copeland Borough Council, the Environment Agency and the coal authority’s help to address the root cause.
“We’re working day after day to get people to help us find a solution and come together to get it sorted and get the harbour back to how it should be.
