To understand why Maryland's Chesapeake Bay Critical Area Law is not working particularly well, one need look no further than to the Queen Anne's County couple who wanted to build a parking garage on their waterfront lot. Last month, an Eastern Shore judge denied the couple the variance they needed to build it - but only after a yearlong debacle that easily could have been avoided.

What's so bad about a three-car garage? By itself, not all that much. But the problem is that the more impervious surface created near the bay and its tributaries, the more harmful runoff pours into the water. The Critical Area law limits property owners to how much impervious surface they can build; the garage in question clearly exceeded that limit.

The real problem lies with the Queen Anne's Board of Appeals' decision to approve a variance allowing the garage. Its rationale? The board didn't see how the project would hurt water quality, and it didn't want to force the owners to tear up an existing driveway to offset the impact of the new construction.

The Critical Area Commission took the matter to court, and in a sternly worded opinion issued last month, retired Queen Anne's County Judge John W. Sause Jr. found that there was "not one scintilla of evidence to support the granting of the variance in this case."

Too bad it had to go so far before reason prevailed. But under current law, the Critical Area Commission doesn't have the right to veto local zoning decisions. It was only because the commission's staff chose to pursue this particular case - and appeal the decision - that the variance was overturned.

This is but one example of why the 24-year-old Critical Area law needs to be strengthened. Gov. Martin O'Malley is seeking legislative approval to do just that, and yet on the subject of variances, it falls woefully short. The governor's proposal cracks down on "after the fact" variances - those issued to property owners when they build first and ask permission retroactively - but it doesn't alter the run-of-the-mill variety.

The evidence suggests local governments bend too easily to the needs of property owners. Over the last three years, 90 percent of 1,128 applications for variances have been approved. Critical Area Commission staff try to monitor these decisions, but their oversight authority is limited.

That needs to change. The commission should be able to veto a variance or have the power to decide which ones should be granted. There is ample precedent for this in state programs that require landowners to get permission to build on tidal or nontidal wetland.

Local governments have demonstrated an inability and perhaps an unwillingness to enforce the Critical Area law. They lack the scientific expertise and lose sight of what should be their guiding concern - protecting the health of the Chesapeake.

The governor's proposal is a good first step, but it needs to be tougher. The General Assembly should make the Critical Area Commission a genuine gatekeeper for what happens within 1,000 feet of the shoreline. Without that reform, the bay will continue to suffer its slow death by a thousand poor land-use decisions.