The streetlights along a western stretch of Central Park were “blazing away in the middle of a sunny day,” said Bill Hewitt, who lives on the Upper West Side of Manhattan. It seemed silly, not a big deal. “Someone forgot to turn a switch, I thought,” Mr. Hewitt said this week. “An anomaly.”

The next day, the lights were still on. And the day after that. That was back in the early summer. Now — or, at least, as of Tuesday, the brink of winter — the lights are still on during the daytime, about six months after Mr. Hewitt first spotted them and began a quest to find someone in city government who would turn them off or explain why not.

Mr. Hewitt, a writer and teacher on environmental issues, worked for many years in the State Department of Environmental Conservation. So he knows his way around government and is not thrown by detours. Logically enough, his first call was to the Central Park Conservancy, the private organization that maintains the park. The conservancy informed him that the streetlights in the parks are the responsibility of the city’s Transportation Department.

The city has 250,000 streetlights in the five boroughs and says that it is a “national leader in using sustainable lighting,” citing a multiyear project to convert all the streetlights to LEDs (light-emitting diodes). The idea is to save money on replacement and on energy. All 1,800 fixtures in Central Park have been changed. They are supposed to come on at dusk and go off at dawn. Inevitably, things break, need repairs, and in the process, a whole grove of lights may have to stay on in order to figure out which ones are not working.