Electric rates for Seattle City Light customers will rise 30 percent over the next six years under a proposal just passed by the City Council.

A typical residential bill of $65 in 2019 would grow to $85 by 2024. The 4.5 percent average annual increase would equal an additional $3.26 per month or $39.12 per year for a typical residential customer, the utility said.

Even as the city’s population balloons, with new residential and commercial buildings rising in nearly every corner of the city, electricity consumption is declining, due to advances in energy efficiency, City Light said in its latest strategic plan. Electricity use is expected to continue to decline.

Though the utility considers conservation efforts a victory, costs associated with maintaining hydroelectric dams, wires, poles, and other infrastructure are placing a significant strain on its budget. Labor, raw materials, and construction services also contribute to increasing costs, City Light said.

“These costs do not shrink when customers conserve energy,” City Light said in its plan.

The utility plans to reduce capital spending by $240 million over the next six years, a 9 percent reduction, according to the plan.

Councilmember Teresa Mosqueda said the 4.5 percent increase represents a dramatic decrease from the original proposed rate increase of 8-10 percent.

The rate increase comes as Seattle City Light is rolling out new smart meters throughout its system. The meters, which measure consumption and communicate that data wirelessly to the utility, are costing $17.4 million more than projected, which was first reported by Crosscut.

During a council briefing Monday morning, Mosqueda noted that “there have been some glitches” with electric bills recently. She said her office is looking into a customer's bill which was three times higher than it was supposed to be.

“If you have seen a change in your City Light bill, take a look at it, make sure that it’s accurate,” Mosqueda said.