A nongovernment environmental organization on Tuesday urged Tokushima Prefecture and the Construction Ministry to involve citizens in a review of a controversial dam project and ensure an adequate environmental impact assessment is carried out.

The request is the result of a five-month comprehensive review on the environmental impact of the dam project by a subcommittee of the Nature Conservation Society of Japan. The document calls for a thorough environmental impact assessment by an independent third party and for local citizens to be allowed to participate in a review addressing the necessity of the project. A list of suggestions by the 11 members of the review committee were submitted with the statement.

These include recommendations that less expensive alternatives to the 100 billion yen dam project be considered, as well as knowledge and technological expertise gained from similar public works projects, such as the Nagara River dam in Gifu Prefecture, be used to gauge the impact on water quality and wildlife.

Controversy over the dam project grabbed national attention early in February after the Tokushima Municipal Assembly rejected a request by nearly half of the city's eligible voters, or around 100,000 people, who signed a petition requesting a plebiscite be held on the issue.

The controversial project calls for a 720-meter-long dam to replace a stone barrier for flood control purposes with gates that can be opened and closed to adjust the volume during times of high water, as well as a highway on top of the structure.

However, citizens are concerned that the project may ravage the natural environment and is an unnecessary waste of tax money.