Aquatic Weed a Noxious Symptom of Pollution

Boatman Jorge Chacra cuts his engine and grasps a long pole to push his way through the thick, bright green layer of weed floating on Puno Bay.

Just off shore on Lake Titicaca, the lawn-like carpet of tiny aquatic plants looks deceptively natural against the blue sky.

Chacra, who earns his living taking tourists to the famous floating reed islands, doesn’t want the tangled green mass clogging the engine. He echoes the concern of many who make their living on the world’s highest navigable lake: The plant is a worrisome nuisance.

“It ruins the motors, and it ruins the fishermen’s net,” Chacra said.

Experts say the plant--known as “water lentil” or lenma gibba--is a symptom of a deeper, more serious problem: the contamination of Lake Titicaca.

Pollution is quickly turning Puno Bay into a foul urban port, smelly and strewn with trash.

Officials worry that the pollution will turn off tourists.

It threatens to expand beyond the bay and contaminate the city’s drinking water, nearly 80% of which comes from the lake itself. In recent months dirty water has extended to within a mile of the city’s pumping station.

Biologist Juan Ocola of the Binational Authority of Lake Titicaca says the lenma is flourishing because it lives on the nutrient-rich human sewage flowing into the bay.

“It’s very difficult to find it in clean water,” Ocola said.

The binational authority includes officials of Peru and neighboring Bolivia, who are working jointly to resolve environmental problems on the cross-border lake.

About 350,000 cubic feet of raw sewage a day flows into the shallow bay, which covers an area of about 3,950 acres, Ocola said.

The pollution is already affecting the local flora and fauna, as well as the health of people living in Puno.

“The native fish don’t exist there anymore. It’s too dirty,” Ocola said.

Puno mayor Victor Torres said the root of the problem is a population explosion in the lakeside city, 525 miles southeast of Lima.

In the last 20 years, Puno, a trading and tourist center, has grown from a city of about 40,000 people to slightly more than 100,000 today, according to census figures.

“When Puno had a small population, the waste water entering the bay did not have any major effect. Now the population has increased too much and the bay cannot support it,” Torres said.

Besides the raw sewage pouring into the bay, the lack of storm drains in Puno contributes to the fouling of the lakeside. During the rainy season, from November through March, garbage, debris and mud are washed directly into the lake.

The pollution has grown worse because of a drought over the last three years that has caused the lake to drop 6 feet from its normal level, 12,572 feet above sea level. The lower water level concentrates the pollution in the bay, which has an average depth of only 10 to 11 feet.

Although the contamination of Lake Titicaca is most critical around Puno, the biggest city on the lake, pollution is also coming in from eight to 12 other cities and towns that either front on the lake or are on tributaries feeding into it, Ocola said.

“If something isn’t done to control the situation, in the next 10 to 15 years we’ll have pollution problems very similar to what we now have in Puno Bay,” he said.

The concern is that the lakeshore could become a wasteland, although the open expanses of the huge, deep lake are not yet seen as threatened by the pollution. Lake Titicaca covers an area about three times the size of Rhode Island, with a depth of up to 890 feet.

Efforts to control the problem are just getting off the ground.

The government has began long-overdue repairs to a sedimentation lagoon so that waste particles settle out before the water flows into the bay.

The Japanese government is considering aid that Torres says includes building a waste water treatment plant and developing a garbage collection system for the city.

The U.N. Development Program recently announced plans to spend $4 million over the next five years to protect the lake’s natural biodiversity.

The U.N. plan includes efforts to reintroduce native fish and plant species and the promotion of traditional conservation. One idea is to use the tortora bulrush--used for making the famous reed boats used on Lake Titicaca--as a natural method of cleaning effluent produced by small lakeside communities.