The city has pledged to make more than $3.5 billion in improvements to its sewage treatment system and will pay a $1.6 million fine, the U.S. Environmental Protection Agency and state Department of Health announced yesterday.

A consent decree was filed in federal court in Honolulu yesterday following an agreement between the city and federal and state governments and three environmental groups that had sued the city.

The $1.6 million fine to be paid by the city will be split between the federal and state governments. The fine is to resolve violations of federal and state law for past sewage spills, such as when a sewer main break forced the city to discharge about 50 millions gallons of sewage into the Ala Wai Canal in 2006.

The settlement requires the city to improve its sewage collection and treatment systems.

"This consent decree or settlement … binds the city to make these improvements," EPA spokesman Dean Higuchi said. "The goal is to get the system to work and to be upgraded and maintained."

More than $3.5 billion in sewer construction projects and waste-water treatment plant upgrades are planned over the next 10 years to comply with the Clean Water Act.

The settlement is subject to a 30-day public comment period and court approval. To see the consent decree, go to www.honolulu.gov/mayor/wwconsentdecree.htm.