Scientists and Divers Join Forces to Seek Solution to Messy Problem That Threatens the Caribbean Reef off Mexico’s Yucatán Peninsula

As travelers flock in record-breaking numbers to the beaches of Quintana Roo in Mexico, an unwelcome result is the enormous increase in sewage, and not just from visitors, but also from people who have moved to the state to take good-paying jobs in the tourism industry. Quintana Roo, which is in the Yucatán Peninsula, already receives 4 million visitors per year, and the government predicts that number will increase to 11 million by 2025. For every tourist who visits the area, there are three Mexicans working in, or dependent on, the tourism industry, which means the coastal population could grow to 33 million in the next 21 years, making it one of the fastest growing areas in all of Latin America. Though large resorts are required by law to treat their own sewage, many residential communities lack sewage treatment plants, and even existing plants are problematic, since some of them inject treated waste into deep wells that contaminate the peninsula’s complex underwater river system.

“I think we’re sitting on a time bomb,” warns Charles Shaw, science director at the Centro Ecológico Akumal (CEA, for its name in Spanish). Akumal is located in the heart of the Maya Riviera: the 80-mile stretch of coast between Cancún and Tulum that is the site of the region’s most intensive development. The number of hotel rooms built along the Maya Riviera during the past seven years equals what was built in Cancún during the past quarter-century, and it will be the site of most of the 15,000 rooms slated for construction in the state during the next five years.

Shaw, a retired geology professor who has spent several years promoting alternatives to current, inadequate sewage systems, explains that the region’s unusual hydrology, which consists of more than 300 miles (500 kms) of underground rivers and a very shallow water table along the coast, makes existing methods of dealing with sewage, which includes ignoring the problem completely, dangerous for people and marine life. He points out that the sewage treatment plant for Playa del Carmen – the Maya Rivera’s principal tourist destination – can handle only a portion of the city’s waste, whereas most of the area’s other towns lack treatment plants.

With funds from the Summit Foundation and Community Foundation, CEA has launched an educational campaign and is investigating practical alternatives to the current status quo for sewage and solid-waste management. The Summit Foundation has also supported the work of the Quintana Roo Aquifer System Research Center (CINDAQ), which is mapping the region’s underground river systems, testing their water quality, and trying to determine the sources of pollution.

“We all live on a very fragile limestone platform, and below us is an underground river system that flows toward the reef,” says CINDAQ founder and director Sam Meacham , who lives in Playa del Carmen. He explains that lack of awareness about the existence of the river system and its vital role in supplying potable water to Quintana Roo’s residents hinders efforts to protect the groundwater. CINDAQ, which was founded by experienced cave divers, is diligently exploring and mapping coastal cave systems and documenting the human impact on them.

He adds that most of the people who live in Quintana Roo moved there from other parts of Mexico and have little knowledge of the local environment. He gives presentations on CINDAQ’s work to an array of audiences and is designing educational kiosks for some of the caletas – intricate coves where subterranean rivers flow into the sea – that have been developed as tourist attractions.

CINDAQ’s primary work is to explore and map the area’s flooded cave systems, which connect hundreds of large, natural wells, through which the rainwater that falls on the Yucatán Peninsula ‘s interior flows to the sea. CINDAQ divers have mapped more than nine miles (15 kms) of unexplored caves, called cenotes, in the Ox Bel Ha system, which includes the longest flooded cave in the world. Among their discoveries are six possible archaeological and paleontological sites – one of which contains the remains of what is thought to be a Gomphothere, a prehistoric relative of the elephant. In a cenote some four miles (7 km) inland, they found a tarpon, a marine sport fish, which illustrates the connectivity of the underground rivers with the sea.

CINDAQ works with a network of hydrologists, archaeologists, biologists, and other experts who benefit from their cave exploration and analyze the information they collect. The divers photograph prehistoric sites and collect samples for later analysis. “We act as their eyes and their hands,” says CINDAQ diver Steve Bogaerts. “We give them x-ray vision, but it’s up to the scientific community to make sense of what we find.”

As Bogaerts checks his equipment for a dive into an underground river that flows into the sea at Tres Rios, north of Playa del Carmen, he explains that cave diving is very equipment-intensive, that they carry back-ups for everything, and often leave tanks along the route with two-thirds of their air left in them, to breath on their way out. Because their air bubbles knock sediment from the ceilings of some caves, visibility can be extremely low on their way out, which is why they always lay a line with directional markers to guide them back out of the cave. “It’s an alien environment,” he says. “You don’t have the luxury of surfacing for air. So if anything goes wrong, you have to be able to sort it out where you are.”

The Yucatan Peninsula ‘s caves are home to some 38 fish and crustacean species and contain cathedral-like chambers with stalactites and stalagmites that formed during the ice ages, when a drop in sea level left them high and dry. Meacham estimates that CINDAQ divers have thus far mapped about 25 percent of the flooded caves along the Maya Riviera, where an underground river system connects nearly 100 cenotes with each other and the sea. The group’s divers are concentrating their efforts in 2005 on the Ponderosa Cave System, near the resort development of Puerto Aventuras, where they plan to implement a water quality monitoring system.

Water samples collected during an exploratory dive in that cave system contained fecal matter, which Meacham suspects came from a nearby resort. The cave explorations will further CINDAQ’s goal of documenting the impact of tourism development on the underground river systems. Meacham and Bogaerts already encountered one very tangible impact of the industry’s impact, when they found that builders of a resort under construction had punched a cement column directly into an underwater cave.

Akumal is one of the Maya Riviera’s most popular areas and where CEA has focused most of its work. Akumal’s beachfront property is dominated by vacation homes and time-share developments, whereas the land to the north is slated for a massive resort. To the west is the community of Akumal Pueblo, which is rapidly expanding to accommodate workers for the nearby mega-resort. The Japanese government financed recent construction of a sewage treatment plant for Akumal, but homes have yet to be hooked into it, so the community continues to rely on septic tanks and out-houses.

CEA plans to create a model Integrated Waste Management Center in an abandoned quarry north of Akumal Pueblo, once the government gives them permission to do so. CEA executive director Paul Sánchez laments that the quarry is currently being used as an illegal dump, where trucks that pump out septic tanks have discharged their sludge.

CEA promotes the use of composting toilets and constructed wetlands as alternatives to septic tanks, which are inadequate for the area due to its shallow water table. CEA hopes to use the quarry site to educate people about recycling, which the organization has spent years promoting in the area’s communities and resorts. Sánchez explains that changing the way sewage and solid waste are handled in the area is an important, but daunting task. He says local governments still send all their garbage to open air dumps, some of which are right next to cenotes. He also cites instances of trucks that pump out septic-tanks draining their cargo into cenotes.

The impact of sewage on the coral reef is hard to document, due to the quick dilution of coastal effluent. But Eric Jordan, a coral expert at Mexico’s National Autonomous University, notes that since the region’s waters naturally suffer a dearth of nutrients, the slightest increase in their nutrient content can have an impact on the natural balance.

“Sewage treatment is more complicated in this region because the idea is not merely to remove the pathogenic bacteria, the goal of traditional sewage treatment, but also to remove the nutrients,” he says, adding that the reef has suffered an increase in bacterial diseases in recent years. While this phenomenon has been linked to high water temperatures associated with global warming, Jordan suspects pollution also plays a role. “The effect pollution has on a reef is much more grave than if a ship or a hurricane were to hit it,” he emphasizes.

Sánchez reports that people in the region are finally talking about waste management issues, since Cancún recently exhausted the capacity of its garbage dump and has no alternative plan for what to do with its waste. “A few years ago, waste management wasn’t even an issue in this region,” he remembers. “Now it is in the headlines every day.”

To keep the sewage problem on the agenda, CEA is a member of the sub-committee for waste management of the Municipality of Solidaridad, which includes Tulum and Playa del Carmen, and is upgrading its laboratory and registering it with the Mexican government, so the group can work with CINDAQ divers to quantify pollution of the cave system and coastal waters.

–David Dudenhoefer

Contacts: Centro Ecológico Akumal, Apartado Postal 2, Akumal, Quintana Roo, Mexico 77760, tel-fax +52-984-875-9095,,; Sam Meacham,

Learn more about CEA’s work in the Eco-Index:


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