The performance of the city's curbside recycling program seems to be sagging a bit.

Yes, the average amount of recyclables being pulled from the trash has dropped by about 15 percent over the past year, according to a survey by the city Department of Environmental Services. Even so, there's no cause yet to follow the lead of other cities and bring in the big guns: issuing fines to homeowners who decline to sort trash into the recyclable and nonrecyclable bins. The kinder and gentler way of stopping the slide would be through education, not penalty — for now.

The city has been at this enterprise for some time, phasing in its curbside collections to comply with a 2006 City Charter amendment that added recycling to city duties. There was some education at the outset so that people would understand how trash gets sorted.

It's clearly time to ramp up that effort again, and to raise the volume. Next month the program will expand into West O'ahu, including the populous Makakilo, Waikele, Waipahu and 'Ewa Beach communities.

It's an opportunity to arrest a declining rate of adherence to what are now voluntary sorting rules. The rate of "contamination" — nonrecyclable material being placed in recycle bins — has more than doubled, from 3.5 percent at the program's start to a high of 7.5 percent at the end of last year.

Todd Apo, who chairs the City Council, rightly concludes that as the recycling program expanded, so did the number of people who didn't know, for example, that only certain kinds of plastic can be recycled. And overall recycling totals could rise if people learn what to divert from the gray catch-all bins.

Cities with the toughest recycling laws, such as San Francisco, have used noncompliance fines to good effect. There may be a point at which Honolulu must follow its lead.

But not yet. Full and voluntary compliance by an informed public should be the target, before any big guns get fired.