(This article originally appeared in the December 2012 issue)
Roatan’s population and development booms of the past decade have outpaced the capacity of the island’s infrastructure to treat its wastewater and of the surrounding marine environment to safely absorb it. In many parts of the island the population is too dense or development is occuring too close to the water for septic systems to work effectively. Only a tiny fraction of sewage receives municipal treatment. Recent scientific measurements indicate this sewage discharge is reducing coastal water quality and clarity and damaging the reef.
No one seems to know how much sewage is produced on Roatan. But the consensus of informed opinion is that there is a lot more of it now than 10 years ago, that most of it is untreated and that it is contaminating the coastal waters and damaging the reef on which the island’s tourist economy depends. When only 20,000-30,000 people lived on Roatan and most of their sewage went straight into the ocean, that was okay, because the ocean could dilute it, said Samuel Rivera, an engineer with Acme Environmental Solutions. However, he said, now that the population is more like 80,000 and is very concentrated on some parts of the island, “those things become a serious problem.”
Neither Harvey Levy, chief of sanitation for Roatan Municipality, nor Lydia Medina of the environmental office could provide an estimate of the volume of sewage produced on the island. But they confirmed very little of it receives municipal-level treatment. Roatan has only two municipal treatment plants, one of which was installed only a year ago and neither of which is operating at anywhere near its capacity or treating a significant volume of the island’s sewage. Some communities and resorts have their own plants. But most sewage on the island goes into septic tanks of varying quality or is discharged directly into gullies, creeks or the ocean. “I’d say a majority is not treated,” said Dan Taylor, Rivera’s boss at Acme.
Ian Drysdale of the Healthy Reefs Initiative said the discharge of untreated sewage was noticeably reducing the water quality and visibility around Roatan and the other Bay Islands. Waters around Caribbean reefs are clear and attract tourists because they are in deserts with no nutrients, he said. Human sewage adds nutrients, fostering growth of macro algae.
“The trouble with macro algae is that it grows faster than corals, so it smothers them,” said Drysdale. “We have seen a huge increase” since monitoring for macro algae off Roatan began in 2006, he said.
Macro algae increased sharply at six of the seven monitoring points around Roatan between 2006 and 2009, with an average increase of more than 250 percent. Data from 2011 are to be published this month and are expected to confirm the trend, said Drysdale. In addition, he said, a 2011 study by scientists at the University of Georgia and Rollins College in Winter Park, Florida, linked a disease in elkhorn corals, which are common in the Bay Islands, to a bacterium found in human intestines.
To stem this problem, Drysdale said Roatan needed to, among other things, establish local regulations for how to build a proper septic tank.
“A septic tank that is well built reduces about 80 percent of the nutrient load,” said Drysdale. Septic tanks hold wastewater and allow the solids, containing most of the nutrients, to settle while the liquids pass into a “leach field” to percolate through the ground so soil microbes can digest the remaining nutrients. However, he said, “What people do here is a bottomless pit with sand and gravel, and the walls have holes in them. That defeats the whole purpose of a septic tank.”
Taylor of Acme Environmental Solutions adds that septic systems become ineffective as the population density increases, as is happening on Roatan.
“When on the island there were houses every half an acre, having septic systems was satisfactory” Taylor said. But as density has increased, “there isn’t adequate treatment area for the leach fields.” Also, said Taylor, septic tanks must be at least 18 inches above the groundwater table to be able to properly leach. Much development on Roatan, such as in West Bay, is below that level, he said, meaning wastewater from the septic tanks should be pumped to higher ground, or another treatment method should be used. In high-density areas, said Taylor, centralized treatment plants employing aerobic microbes (those that live in oxygen as opposed to in the ground) are required. “Aerobic bugs are orders of magnitude more efficient than anaerobic bugs.”
Such a plant was built near the airport about 10 years ago with a loan from the Interamerican Development Bank obtained through
the Honduran Ministry of Tourism. It was designed to treat all the sewage from Coxen Hole. However, the Municipality was unprepared to operate the plant, said Taylor, and users could not be persuaded to connect to the system. Today Taylor estimates the plant treats 3-4 percent of Coxen Hole’s sewage. Levy, the Roatan sanitation chief, says it’s 10 percent.
Skip forward a decade and the Municipality decided to put a treatment plant in West End, where both geography and rapid development were causing water contaminants to accumulate, endangering the area’s dive tourism. This time the plant, built by Acme, was paid for with local and national funds. Once again, though, the Municipality installed collection lines, but individual homes and businesses were supposed to connect to them on their own. No system for charging users was set up in advance. To date only a handful are connected. Taylor said Acme was treating their waste anaerobically and running the plant only one or two days a week just to keep the equipment functioning. “There are certainly some similarities” to Coxen Hole’s situation, Taylor said.
Acme’s contract for the plant included a one-year operation agreement, which would have expired this month, but Taylor said Acme unilaterally reinterpreted the terms to count operating days rather than calendar days. He said Acme was negotiating to extend the contract.
Drysdale said West End’s water boards were working on a payment and management scheme to make the plant viable. Meanwhile, most West Enders are still using septic tanks. Nonetheless, Drysdale sees West End as a template the Municipality should use to find solutions for other communities. At the same time, he said, tourist resorts and new developments should be required to treat not only their own sewage but also that of their neighboring communities. “If they’re making money off the reef, they should be giving money back to the reef,” said Drysdale.
However, Taylor said most of the big resorts were already investing in treatment systems. Some do not use the right technology, he said, and not all of them properly maintain their systems. But he does not think the resorts are the main contributors to Roatan’s wastewater problem. “The places where the biggest challenges are,” said Taylor, “are in places of high population density: Los Fuertes, French Harbour, Coxen Hole.”