Naval Base Guam is making about $50 million in upgrades to its wastewater treatment plant and sewer system as part of an agreement with the U.S. Environmental Protection Agency following a 2008 violation of the federal Clean Water Act, the EPA said this week.

The agency cited the base in 2008 for discharges that exceeded water-quality permit levels and for lack of controls on storm water runoff, including drainage from construction sites, according to an EPA publication on the violation findings.

But since then, the Navy has “substantially addressed” the problems cited by the EPA and has agreed to continue improving base treatment systems, according to the agency.

Naval Base Guam unveiled the first $37 million in improvements to its Apra Harbor wastewater plant earlier this month and is planning at least another $13 million in upgrades to its sewer system, including the repair and replacement of more than 30 miles of sewer lines, force mains and laterals.

The base has also agreed to minimize the release of metals, oils and other pollutants from shipyard and industrial sources, the EPA said.