SEOUL - South Korea launched an ambitious and costly project this week to overhaul its four major rivers in a way the government says will be a model for green growth but conservationists say will do far more harm than good.

President Lee Myung-bak, a former CEO of Hyundai construction, has been campaigning globally to show his country as an environmental industry leader, with the four rivers project at the center of his plans to reshape Asia's fourth largest economy.

Critics said the project is more about local politics, aimed at creating jobs in rural areas that will provide crucial votes for Lee's conservative camp in South's Korea's next presidential election in 2012, which is when construction is due to end.

South Korea has budgeted 22.2 trillion won ($19.23 billion) to dredge, dam and beautify the four waterways with golf courses and bike trails in the plan that is supposed to increase supplies of fresh water, improve water quality and prevent flooding.

Upon completion, not only will flood control be possible, but cruise ships and various water sports will be seen in the rivers, Lee said on Sunday to mark the start of construction.

South Korea has few supplies of fresh water and two of its major rivers flow from rival North Korea, which has built dams along the waterways that can severely alter water flow.

Local governments are frantically trying to include their own development plans into the massive project and construction companies are said to see it as the biggest windfall in the country's history, said the Chosun Ilbo, the biggest newspaper and a backer of Lee, in an editorial this month.

Jun Yong-ki, an analyst at Meritz Securities, said the project would certainly provide some liquidity into a struggling construction industry, which will help the labor market.

MASSIVE DREDGING

Environmental groups said pouring concrete down river banks and building 16 planned dams will decrease or alter water flows, killing fish and threatening water quality.

Massive dredging will release silt into the water and could damage water quality permanently without proper planning, they said.

About 420 South Korean groups have joined forces and plan to file this week a joint lawsuit to stop the four rivers project before they say it will wipe out habitats.

By damaging the rivers, they will be destroying the building blocks of the ecosystem, said Jung In-chul, an activist with Green Korea, a leading environmental group that is helping to spearhead the lawsuit.

The controversy over the project could slow down things in parliament, where many of Lee's pro-business economic reforms have languished. Opposition MPs have threatened to hold up measures until they receive more data on funding and the environmental impact of the river projects.

The government says it will use advanced technologies in dam construction that will increase water supply and protect fish stocks with gates that allow fish to swim upstream and can also manage water flows, leading to cleaner rivers.

It also says it will use the dams for hydroelectric power stations to provide clean energy for the resource poor country, which relies heavily on nuclear power.

(Editing by Jonathan Hopfner and Bill Tarrant)