O’Fallon says in its complaint that it pays more than $1 million annually for its 4,444 lights. Switching to a customer-owned rate would save it $820,000 annually, its complaint says.

O’Fallon communications director Tom Drabelle declined to make a city official available to discuss its costs or the PSC complaint.

Ballwin says it pays $500,000 each year to power its 2,159 lights. Buying the lights and switching rates would save it $400,000, the city says.

Critics say the lights don’t appear to need much repair. And the higher costs can’t be explained by Ameren’s initial investment to install the lights, they say, because developers are often required to put in the lights when they build a new subdivision.

“A lot of the lights are installed by the builders,” said Tim Fischesser, executive director of the St. Louis County Municipal League. “So a lot of what we’re trying to figure out is why it costs $22 a month when there’s almost never maintenance needed.”

Other cities are watching the Ballwin and O’Fallon complaint.

“In terms of what we pay for utilities, the cost for street lighting … is by far the most expensive utility-wise,” said Marty Corcoran, Maplewood’s city manager.