Honolulu will be hiring a consultant to study ways the city can pay for nearly $5 billion in upgrades to its sewage and wastewater treatment systems.

The yearlong study will follow in the wake of a consent decree the city recently entered into with the U.S. Environmental Protection Agency.

The city has estimated the upgrades could require yearly 3 percent to 5 percent sewer fee increases for about 25 years.

Possible alternatives include abandoning rates that can vary depending on usage in favor of a fix monthly sewer fee. There could also be rate relief for fixed and low-income customers.

The consultant is expected to be chosen next month, with the study getting under way in October.