"Apart from direct pollution from the flower farms, uncontrolled population growth of poor people in Naivasha has been the main source of pollution," Andrew Enniskillen, the chairman of Lake Naivasha Riparian Association, told reporters this week.

"The number of people living within five kilometres of the lake has risen from 50,000 in 1980 to 250,000 this day," he said, adding that job opportunities in the farms had attracted an increasing number of people to the town.

Falling water levels, pollution caused by agriculture chemicals, over-exploitation of fisheries as well as fuel leakage from farm machinery are taking their toll on the only non-soda lake and its biodiversity.

"This lake and its wetlands have been overused and polluted, mostly by chemicals from flower farms and this has affected its biodiversity," said Stanely Mbugua, a fisherman who has depended on the lake since 1966.

Flower exports have become Kenya's second major foreign exchange earner after tea and tourism, bringing more than 100 million dollars into the economy each year.

Torrential rains in Kenya in 2000 washed huge amounts of chemicals into Lake Naivasha and the eutrophication of the lake, 80 kilometres (50 miles) northwest of Nairobi, killed "millions of fish and other aquatic life," according to an environmental researcher.

Fertilizer residue and other agrochemicals have been trapped in the soil along the lake's shores next to the flower farms, according to the Consultative Group on International Agricultural Research (CGIAR).

"Even birds -- fish-eagles and kingfishers -- that captured and ate the poisoned fish died at worst or have been affected," a CGIAR researcher who asked not to be named told AFP.

A government fisheries officer, Rodrick Kundu, said the death of millions of fish in 2000 coupled with overfishing had forced the government to slap a ban on fish harvesting for a year.

Mbugua, a former flower pruner, said that some farms were still using banned chemicals, which have affected the health of farm workers and polluted the environment.

But flower farm managers beg to differ.

"We have excellent water and sewage treatment facilities here. We don't let chemicals into the lake whatsoever. We are very conscious of our farming techniques," said James Kelmanson, the technical manager at the Dutch-owned Oserian Flowers, one of about 30 horticulture farms in Naivasha.

"We understand that environmental conservation is the hallmark of this trade. If we mess, we are done," he said.

Kelmanson said Oserian had developed a new way of fighting fungal diseases without resort to chemicals. Instead the company uses geothermal steam in the greenhouse to get rid of the diseases.

"This method has reduced the use of chemicals by 25 percent," Kelmanson explained.

Lake Naivasha is the key source of irrigation water for an extensive flower belt.

"Too much irrigation has reduced the water levels," said farmer Joseph Kamau, who has lived near the lake for three decades.

Mbugua is pessimistic about the future of the lake.

"We understand why nothing has been done. It is delicate weighing between keeping the benefits from the lake and the benefits of the flowers," he said.

TERRA.WIRE