San José, Costa Rica, since 1956

Experts Warn Lake Cocibolca is Ailing

As a child, Eleazar Morales bathed in the fresh water along the windy shores of LakeColcibolca. “I opened my eyes beneath the water and brushed my teeth with the sand,” said the longtime Granada resident.

But at age 55, Morales says he now avoids the lakeshore like the plague.

Unlike the days of his childhood, the shores of LakeCocibolca today are trashstrewn, and the rivers that feed into it overflow with foul-smelling waste. Still, this “freshwater sea” – as the Spanish called it – is undoubtedly the future source of drinking water for Nicaragua, and perhaps Central America.

“Everyone in this country will have to drink that water sooner or later,” said SalvadorMontenegro, Nicaragua’s leading lake researcher. “It’s the only reserve that can satisfy the thirst of the Nicaraguan population, and the irrigation demands of its arable lands.”

Nicaragua’s new Water Law, passed late last year, establishes that LakeCocibolca – also known as Lake Nicaragua – is a national strategic drinking-water reserve, and calls on the government to create a management plan to protect it.

At 8,000 square kilometers, LakeCocibolca is the hemisphere’s largest tropical lake. But this vast natural resource is threatened by rampant urban development, waste mismanagement, farming, fishing and widespread deforestation, according to environmentalists.

“The river basin is going bald,” said engineer Marceliano Jiménez, of the Nicaraguan Water and Sewage Company (ENACAL).

The lake currently provides drinking water for several small communities on the eastern shore of Chontales – the rural, cattle- raising department across the lake from Granada. Plans are underway to tap the lake for 50,000 residents in Juigalpa, the capital city of Chontales.

Though underground aquifers in the lake’s basin serve as water sources for the departments of Granada, Managua, Masaya and Rivas, experts say that the lake itself will become the main source of drinking water for Granada in less than a decade, and for Managua within 20 years. The lake will also soon be supplying the southern Pacific beach town of San Juandel Sur with water and will quench the parched northwestern province of Guanacaste, Costa Rica, experts say (NT, July 2, 2004).

Nicaragua’s own coastal development boom in the dry Pacific region of the country begs the question: Where will the tourism industry, the economy’s biggest income generator, get its water in the future? LakeCocibolca could be the natural solution.

The water in the lake is plentiful. The mouth of the San Juan River alone discharges 50 times more fresh water than the entire population of Nicaragua consumes – that’s $35 million a day in water resources at current market rates.

Long Time in the Making

Central America was formed as many as 18 million years ago, when the hemisphere’s two continents began merging to create a land bridge.Volcanic and geological forces forged a large, liquid belly button in the middle of the isthmus, which became one of the world’s most unique fresh-water ecosystems.

But now that ecosystem is facing challenges like never before.

Scientists say the biodiversity of the lake’s algae and fish populations is dwindling; decades of unregulated fishing has ravaged the populations of the lake’s great prehistoric predators – bull sharks and sawfish (NT, Feb. 3, 2006). The same may be happening to tarpon populations, according to preliminary studies by Juan Bosco Mendoza, the Fisheries Institute’s representative in Granada.

Some experts blame the lake’s biodiversity problems on tilapia, a non-native – some say “invasive” – fish inadvertently released into the lake nearly three decades ago when flooding broke open the floating cages in which they were being cultivated in a separate lake.

The African fish now accounts for 80% of the catches fishermen are reporting in the lake, according to Montenegro, who founded the National Autonomous University’s Aquatic Resources Research Center (CIRA).

Additionally, tilapia are also being cultivated for export inside floating cages off Ometepe Island.

“There’s something wrong,” Montenegro said of Lake Cocibolca’s ecosystem. “It’s a natural resource and we’re not using it. Worse, we’re destroying it.”

Quality Control

Lake Cocibolca’s drainage system is a complex structure of volcanic formations and dozens of sub-basins and rivers that feed the lake. It also houses five of Nicaragua’s biggest superficial aquifers, and three of its biggest subterraneous ones.

According to a 2007 CIRA study, nearly half of the soil in the lake’s basin is being used for ranching and farming, presenting a slew of environmental disruptions. Ranchers are deforesting plots of lakeside pastureland; rice farmers in Malacatoya and elsewhere are contaminating the lake’s rivers with floodharvesting tactics; sugarcane growers in Rivas are irrigating their crops with the lake’s water and then draining it back into the lake, fertilizers and all; and farmers around the lake are illegally draining it for irrigation during the dry season.

Fertilizer drainage is boosting nitrogen and phosphorus levels in the water, causing a process known among biologists as “eutrophication” – which reduces the lake’s once-complex algae composition and whittles away at aquatic biodiversity.

The cattle industry here still clings to disperse herding techniques introduced by the Spanish in colonial times, leaving a larger environmental footprint than more modern eco-friendly herding,Montenegro said.

Urban expansion, however, is the most intense contaminator of the lake’s basin, experts claim.As urban areas grow, so too do open air garbage dumps, which threaten to leech into the water.

In addition, less than 40% of the 1 million Nicaraguans who live along the lake’s basin receive proper wastewater services.

In Managua, industrialization and urbanization have caused heavy contamination of Lake Xolotlan – also known as Lake Managua – which Montenegro suspects is seeping into Lake Cocibolca and increasing future costs of tapping the great lake (see sidebar).

The lake’s 400 islands pose their own set of problems. Residents of many privately owned isletas are dumping waste right into the lake, according to Ligia Flores of the Ministry of Environment and Natural Resources (MARENA). Other protected islands, such as Zapatera, face rife deforestation – a problem that causes runoff, pushing aquatic life deeper into the lake and increasing future purification costs. MARENA says it embargoed 4,600 trees that were cut illegally on Zapatera Island last year.

“The birds and monkeys’ ecosystems are being taken away and they can’t migrate. It’s a loss of biodiversity,” Flores told The Nica Times.

On the south end of the lake, nearly half of Cocibolca’s shore runs along the Costa Rican border, where a combination of heavy rains and steep mountains are washing pesticides used on cash crops – macadamia nuts, bananas and rice – right into the lake.

Montenegro calls the toxic problem of pesticides – also used by Nicaraguan farmers – “the biggest threat to the lake’s biodiversity.”

A Decade of The Same

Eleazar Morales, who used to swim in the lake as a child, is now the manager of the archives at the cultural center Casa de los Tres Mundos in Granada, where he teaches students about the grim future that awaits them if they don’t care for their lake.

A CIRA report, conducted more than a decade ago, tested 20 samples of lake water from different points offshore and four rivers that feed into the lake, and found levels of fecal coliforms as high as 60 times above those considered suitable for bathing.

It also found high levels of e. coli, “drastically” high levels of pH, sodium and chlorine.

MARENA has since shut down one contaminating leather factory, and says it is pursuing actions against other contaminating factories in Granada.

But little else has been done to fix the pollution problem since the report first brought the issues to light in 1996. Back then, only 21% of the city had sewage service and only 45% had trash service. Today, only 25% of Granada residents have sewer connections, according to estimates by ENACAL’s Granada delegate Elvin Hernandez. Though some have hooked up to the sewer system illegally or have septic tanks, a large minority is still dumping wastewater straight into Granada’s riverbeds, which flow into the lake.

“We’re about at the same level as much of Africa,” Hernández said.

ENACAL faces an uphill battle of connecting the rest of the community to the 40-yearold sewer network, which is so overburdened that it doesn’t properly treat the wastewaters that are funneled back into the lake.

The Health Ministry this week is scheduled to release a report detailing which parts of the lake in front of Granada are unfit for bathing, according to health inspector Freddy Vallecillo.

In addition to sewage, Granada’s water resources are also threatened by the municipal dump, which is over saturated and build right above the city’s main aquifer.

“We’re above one of the purest aquifers in our city …We need to move as soon as possible,” Granada Mayor Rosalia Castrillo said of the city’s plans to close its dump, known as La Joya.

Morales, meanwhile, says he doesn’t plan to return to his childhood swimming spot until the lake is cleaned up.

“Last time I was there, the air smelled like poop,” he said, wincing behind his glasses. “Instead of improving, things have gotten worse.”

Cross-Contamination: Theory or Threat?

MANAGUA – Salvador Montenegro, the country’s leading lake researcher, says that the heavily polluted waters of Managua’s Lake Xolotlan are cross contaminating Lake Cocibolca through underground seepage at four cubic meters per second.

The seepage has been confirmed by residents living between the two lakes who have wells with water registering the same salty composition as Lake Xolotlan, according to Montenegro.

The latest analysis by the National Autonomous University (UNAN) also found that water samples in the northern part of Lake Cocibolca have algae with similar composition to those of Xolotlan.

Cross contamination is an alarming possibility, Montenegro says, considering that 40 million gallons of wastewater per day and contamination from 1,200 tons of garbage from Managua’s open-air dump are leaking into Xolotlan.

But Montenegro’s theory has failed to convince everyone.

“I have my reservations,” said ENACAL engineer Marceliano Jimenez. Jimenez says that the ground acts as a natural filter to any water that passes underground from one lake to another, helping to clean it of any contamination.

“Some water could be arriving, but not organic material,” he said. “It’s a theory that hasn’t been proven.”

Montenegro says the salty Xolotlan seepage may also be increasing Lake Cocibolca’s salinity levels, which would make tapping it as a drinking water supply a more complicated process in the future.

Because the eight-meter-deep Xolotlan is so shallow, water evaporates from its surface faster than water drains into the lake from its basin. Because its a closed basin, the salt can’t escape, which means the lake is constantly becoming increasingly saltier.

Xolotlan is a “1,000 square-meter evaporating pan” that “will be like the Dead Sea in 200 years,”Montenegro said.

“Nobody wants poor quality water mixing with their drinking water,” he added. “However, there’s no comprehensive management plan for Xolotlan and Cocibolca, A plan should integrate both watersheds.”



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