Sometimes the seemingly simplest solution to a problem creates some unforeseen and unwanted consequences.

The nearly total ban of commercial activity at Kailua and Kalama beach parks — with some exceptions for commercial filming activity — may be the most vivid recent example. Last week the City Council passed Bill 11; its 7-2 tally should have an asterisk, with three of the seven voting yes, "with reservations."

That vote came a mere few weeks after a partial ban took effect, barring activity from 1 p.m. Saturdays through 6:30 a.m. Mondays. The better act by the Council would have been to give that time restriction, enacted under Bill 5, at least a chance to work.

Mayor Peter Carlisle should veto Bill 11, which would have the effect of reinstating Bill 5 while his administration revisits the best way to regulate park use on a broader, islandwide basis.

The partial ban would have preserved the city’s review through a permitting process and sequestered most of the weekends as a time devoid of all the concessions. The plain fact is that vendors, unregulated, can overwhelm these popular parks, and the city has a duty to draw some bright lines. Enforcement, which is always a challenge, could be at least workable through spot checks for permits throughout the week and more vigilance during the ban periods.

Instead, enforcement becomes an even more difficult proposition. The city lacks the resources to scout the parks for activity, day in and day out. And it’s easy to imagine that ways would be found to circumvent the ban. If the activity involves no cash transactions on site, for instance, can people be prevented from meeting at the beach to engage in them?

Further, there may be activities that the local community clearly favors but would be ejected, too. Bouncer rentals, the inflatable play equipment that are fixtures at children’s beach parties, would now be out, to cite one example. Food trucks on the North Shore and elsewhere are also popular with the public broadly, but they fall under the commercial banner.

One more issue worries Gary Cabato, city parks director: The idea already is catching on with other city parks around the island, with neighborhood boards already pushing for their own bans.

He argues rightly that it would be smarter management of city recreational resources to use a scalpel rather than a meat cleaver. Setting out clear rules for what activities will be allowed and when makes more sense than trying to stand guard over Oahu’s parks, 24/7, which is what a total ban generally requires.

Finally, Cabato said, the city needs to return to a more systematic way of providing oversight. He cited both state environmental law and city administrative rules requiring public hearings and, in some cases, an environmental assessment for activities to be approved. He plans to announce a series of public hearings around the island to give residents a voice in which activities should be enabled in their communities.

That’s a good plan, and the public should take part in devising rules that work for their communities.

Of course, success in any regulatory endeavor relies on adherence. Commercial ventures, for example, need to do their part to comply with any reasonable restrictions set forth. Otherwise, the situation deteriorates and little choice is left but for a total ban.

Managing Oahu’s precious beach recreation requires that a balance be sought between competing interests. Total bans aretoughto sustain — and they’re often not what the majority wants, in the final analysis.