The City of Dubuque has also agreed to spend an additional $3m on improvements to its water pollution control plant and sewer collection system over the next three years and approximately $260,000 on a supplemental environmental project.

As part of the settlement, the City of Dubuque will pay half of the civil penalty to the US, and half to the state of Iowa, which is a co-plaintiff in the case.

The supplemental environmental project will involve the reconstruction of four alleys that incorporate permeable pavement in their design, which will help reduce the flow of storm water into the city’s sewer system.

EPA said the consent decree sets forth a series of schedules for the city’s completion of the various projects to improve its sewer system.