DES MOINES, Iowa — Exactly what Sioux City’s automated traffic cameras have done to improve public safety is debatable, but the more than $1 million they’ve raised to fatten police and firefighter pensions isn’t.

Now new regulations from the Iowa Department of Transportation curbing use of the cameras on state highways and interstates threaten a revenue stream the city has been using to cover gaps in its operating budget.

Sioux City is considering suing IDOT in hopes the courts might invalidate the new regulations.