The Water Authority Cayman has denied claims from private citizens that its sewage treatment plant is leaking waste into the North Sound.

Those statements were made following photos that were e-mailed around Grand Cayman depicting what was described as raw sewage floating in the sound.

Water Authority Director Gelia Frederick van Genderen said claims made in that e-mail were incorrect.

However, pollution is occurring in the calm body of water that is one of Cayman’s favourite boating and tourism destinations, according to both the authority and Department of Environment officials. Evidence of that pollution is beginning to show up in the form of little green and brown coloured plants growing in the water.

Algae is taking hold in some of the near to shore areas of the sound.

According to Department of Environment Director Gina Ebanks-Petrie marine plants tend to proliferate in tropical waters where higher levels of nutrients are available. Waste is one of those nutrients that can cause plant life to flourish.

A department study conducted since 2003 has revealed that marine plant growth is occurring along some areas of the North Sound shoreline.  

What’s causing it isn’t exactly clear.

“There are several possible contributing factors which include: leachate (liquid that drains) from the unlined George Town landfill, out current methods for on-site wastewater treatment and disposal, poorly planned canal developments, fertiliser-enriched run-off from golf courses and other landscaping, and inputs from recreational use of the marine environment,” read a statement from the Water Authority and Department of Environment.

The Department of Environment also noted that large-scale removal of coastal mangrove wetlands to accommodate development, particularly on the western side of the North Sound, had reduced the ability of the environment to make up for the effects of pollution.

“Each of these issues has a direct or indirect impact on water quality in North Sound,” the statement read. “Areas where canals drain into the North Sound are the most affected.”

Growth of algae and other marine plants can cause the water to turn green and cloudy. They can also cause a reduction in oxygen levels in the water at night and reduced sunlight exposure to plants like turtle grass. Lack of oxygen in the water can also kill the local fish population, or drive it away.  

The grimmest news, according to the department, is that there’s no easy way to fix this problem.

“It is not possible to turn back the clock,” the joint statement read. “Changes and improvements need to be made in the ways in which we plan future development and manage existing development.”

One change that needs to occur, according to Department of Environment Assistant Director Tim Austin, involves the continued use of septic tanks on Grand Cayman.

“The water table is very close to the underlying ground level,” Mr. Austin said. “Anything that gets put into the ground eventually makes its way into the marine environment.”

That nutrient rich soil seeps into the water around the shore and leads to growth of seaweed, sea grass and the like.

“They call it the ‘island-halo’ effect, because all the water comes out at about 30 feet around the Island and you start to see this noticeable difference in algae makeup where these waters are exiting,” he said.

Luckily, Grand Cayman has not seen a massive proliferation of algae in one or two coral reef areas. However, Mr. Austin said there has been an across-the-board increase in algae growth around Grand Cayman.

“That may just be an artefact of declining coral cover,” he said.

The proliferation of algae in areas can lead to a decline in coral reef growth, Department of Environment officials said. The algae make it too difficult for juvenile corals to put down roots and reproduce.

Mr. Austin said Grand Cayman is down to about 15 per cent healthy coral cover around the Island. The first study of coral cover done here in the mid-90s put that number in the high 20s or even 30 per cent in some places.