PORTLAND, Maine — The city of Portland and U.S. Environmental Protection Agency have announced an agreement under which Maine’s largest city would pay the federal regulators $53,250 in fines for discharging sewage into waterways in recent years.

The agreement was treated as a victory by Portland officials, who were able to negotiate the financial penalty down from an initial EPA figure of $177,500. But the fine adds to already-ballooning costs the city faces to control its discharges of untreated sewage.

Portland has already spent or is due to spend $94 million from 1993 to 2014 fixing its aging sewer system and is eyeing new stormwater fees for property owners to help offset more than $170 million in additional upgrades in the next 15 years.

“While we are pleased to have the matter settled and the penalty amount reduced, the city still faces real challenges managing the many complicated aspects of the Clean Water Act,” said City Manager Mark Rees in a Wednesday statement. “Old coastal cities like Portland face significant financial hardships. Separating our sewer and stormwater system is expensive and has been largely borne by the ratepayer with little to no support from other agencies. We need an integrated approach that is both environmentally responsible and not overly burdensome to local businesses and residents.”

The latest penalty assessed to Portland by federal regulators is punishment for so-called sanitary sewer overflows between 2007 and 2009. Because storm drains in many areas of the city still tie into the sewer system, heavy rainstorms combine with regular sewage to create a volume too great for the pipes, pump stations and treatment checkpoints to handle. As a result, the stormwater and untreated sewage floods the system and is discharged directly into waterways such as Back Cove and Portland Harbor.

According to a Wednesday city announcement, much of the city’s sewer lines predate the Civil War, while the pumping stations were installed in the 1960s. The infrastructure is struggling to keep up with storms of increased intensity, the city announcement stated, including a storm last August in which 1.3 inches of rain fell per hour.

The Environmental Protection Agency stated on Wednesday that the overflows occurred on at least 22 occasions in Portland over the past five years.

“Because of the known health risks associated with discharges of raw sewage into the environment, working with cities and towns to proactively manage sewer systems is one of EPA’s highest priorities,” said EPA Regional Administrator Curt Spalding in a statement. “ In New England, overflows from sewer systems are among the largest remaining sources of water pollution. The actions called for in this settlement should result in addressing that problem in Portland.”

In addition to the fines, Portland agreed to invest $45,000 in projects to prevent erosion along 1,000 feet of Dole Brook.

Since 1993, the city has completed more than 100 sewer overflow abatement projects, eliminated 11 of its 43 overflow points and reduced average overflow volumes by more than 42 percent. The projects lined up for the next phase of system upgrades would eliminate sewer overflows into the Fore River, cut Back Cove overflows from 416 million gallons annually to 70 million gallons and reduce overflows into Portland Harbor from 145 million gallons per year to 17 million gallons.

“In partnership with the EPA, we hope to develop a long-range plan with agreed-upon priorities that address the various aspects of sewer and stormwater in a way that is manageable,” Rees said in a statement. “This approach would also ensure that the work and progress made to improve the city’s water quality is recognized.”

Seth has nearly a decade of professional journalism experience and writes about the greater Portland region.