The Enterprise City Council voted to spend $1.4 million for a sewage treatment upgrade.
Engineers say the improvements are necessary to address fines ordered by the Alabama Department of Environmental Management.
That agency fined the city several thousand dollars last year for being out of compliance.
The improvements will be done at the Northeast Lagoon.
Residents and businesses will be paying an additional $10 a month on their sewer bills over the next four years in order to pay for the upgrade.
Once the project is finished, it should last for about 10 years before additional upgrades are required.