AUGUSTA — A proposed 15 percent rate increase in stormwater fees, expected to increase the monthly bill of most homeowners in Augusta by $1.13 a month, would have a much bigger effect on the city of Augusta.

Maine’s capital city has more than 2,100 catch basins, each subject to the fee increase that’s planned by the Greater Augusta Utility District. The city would pay $15,000 a month, an annual hit of $186,000.

Augusta now pays about $1.2 million a year in stormwater-related fees. This increase would require a property tax increase of about 0.5 percent by itself, although City Manager William Bridgeo said that’s far from the only expense projected to increase next year; he’s currently working on that budget.

Bridgeo said the proposed school budget is projected to require a 2 percent tax increase. Health insurance costs for city employees and retirees are expected to grow 15 percent, and changes to the state retirement system, which shifted more of the cost to municipalities, are expected to increase the city’s costs by about $180,000 next year. Taken together, the increases are expected to make for a rough budget year coming up for the city.

“It comes at a bad time, I think,” Bridgeo said of the proposed Greater Augusta Utility District increase in stormwater fees. “I’m anticipating some other, uncontrollable cost drivers that suggest this is going to be a pretty difficult budget year for the city.”

Bridgeo has asked district officials informally to consider phasing in the rate increase more gradually, to lessen the immediate effect on city finances. He plans to make that a formal request.

Ken Knight, chairman of the district’s board of trustees, acknowledged the rate increase would have a significant effect on the city. Officials from the utility district and the city are considering how to lessen it.

“Our biggest customer for stormwater is the city of Augusta, and the district is very understanding about that, and what (an increase) causes in tight budget years,” Knight said. “The city is certainly our largest invoice. The city surely shoulders the burden of catch basin fees.”

Catch basins, also known as storm drains, generally collect water at the street level and direct it into treatment systems.

The utility district, which handles stormwater in the city of Augusta, has 3,678 catch basins, 2,146 of which are the city of Augusta’s.

The proposed rate increase would increase catch basin fees from $46.27 to $53.21 per catch basin, per month, a $6.94, or 15 percent, increase.

Brian Tarbuck, utility district superintendent, said the stormwater fee increase is needed to help cover steadily rising operational costs, and because an analysis of district costs indicated the portion allocated to stormwater management is now slightly below what it should be.

“This corrective action will help us continue to provide the highest quality service to our customers, while allocating costs fairly for all ratepayers,” Tarbuck said.

Knight said complying with federal environmental regulations while preventing overflows of stormwater particularly when combined with sewage into water bodies including the Kennebec River is an ongoing challenge.

“We live beside a river and we’re starting phase four of a four-part combined sewer overflow plan to treat all the stormwater before it goes into the river,” Knight said. “It is becoming a very challenging expense to the district. The pressure on us with stormwater is tremendous, but all of us are for clean water.”

The rate increase would be the district’s first in five years, Tarbuck said, and it affects only Augusta ratepayers and their stormwater bills, not any of the district’s customers for other services in surrounding communities. It would go into effect with the July bills.

In addition to the catch basin fees, the district also would increase the equivalent residential unit charge, which covers the stormwater costs allocated to a single-family dwelling on stormwater bills from $7.55 to $8.68 per month, an increase of $1.13, or 15 percent. A single-family dwelling is allocated one equivalent residential unit, so a typical Augusta homeowner’s total monthly bill will increase by that same $1.13 a month.

Bridgeo said he understands the need for the rate increase; he just hopes to convince district trustees to phase it in more gradually.

“I don’t dispute they need to have a rate increase,” Bridgeo said. “I think the district is well-managed, has a good board, and conscientious staff, but an increase that big definitely has an impact on the city budget.”

A public hearing on the proposed changes is planned for 6 p.m. Monday, in the council chamber at Augusta City Center.

Tarbuck said the fourth, and final, phase of the district’s efforts to prevent combined sewer overflows is required, by the district’s Department of Environmental Protection permits, to be complete by March 31, 2019. Combined sewers convey both sewage and stormwater in the same pipe under normal conditions, taking the combination to the district’s wastewater treatment plant, where it is treated before being discharged into the Kennebec River. During some major rain or snow melt, the amount of combined storm water and sewage exceeds capacity and overflows into the river.

Previous phases of efforts to eliminate combined sewer overflows included most recently a $17.3 million project completed in 2011, which installed massive storage tanks underground at Mill Park to hold the combined water and sewage during major rainstorms to prevent it from flowing into the river. Once a storm subsides, the combined water and waste is sent to the plant for treatment.

Tarbuck said the final phase will involve a new underground storage tank with a capacity of about 1 million gallons, to be located somewhere on the east side of the river. District engineers are evaluating where a tank that size could go.

Keith Edwards — 621-5647

[email protected]

Twitter: @kedwardskj