For more than a quarter century, government leaders have made ambitious promises to restore the health of the Chesapeake Bay - and then promptly broken them with little or no consequence. Small wonder that so many frustrated bay supporters in Maryland and elsewhere are fearful that the U.S. Environment Protection Agency is headed down that familiar path.

But that only partially explains the recent heightened criticisms from the environmental community that the EPA's plan to sanction states that fail to meet pollution-reduction targets isn't nearly tough - or specific - enough. Some at the EPA have expressed surprise at the passionate response, or what one official termed a "sharper" voice, from groups such as the Chesapeake Bay Foundation.

Clearly, two other factors are involved. First, and probably most important, bay supporters have quickly discovered that President Barack Obama's push for greater federal involvement in the Chesapeake Bay's restoration is generating significant resistance in Washington.

There is concern that the cleanup effort has ramifications far beyond the six-state watershed. More aggressive EPA enforcement of water quality standards could easily become a model for the nation in dealing with pollution from diffuse sources, such as storm water run-off - a welcome development for the environment, perhaps, but a scary prospect for polluters.

Within the region, support for the effort could use some bolstering, too. Legislation sponsored by Maryland's Sen. Benjamin L. Cardin and Rep. Elijah E. Cummings to strengthen and clarify the EPA's role in the cleanup (known as the Chesapeake Clean Water and Ecosystem Restoration Act) has so far attracted just 18 co-sponsors from the 53 bay state members of Congress.

Even the Obama administration has failed to endorse it - at least so far. With climate change legislation still trapped in the Senate, it could be the administration has little interest in spending political capital on an environmental issue with little resonance beyond the Mid-Atlantic.

Not to be overlooked as well is the growing suspicion among many people that the Chesapeake's plight has become so desperate that this amounts to, if not a last stand, then perhaps a last, best hope for a turnaround.

Given all that, EPA Administrator Lisa Jackson should realize that as newly installed chair of the Chesapeake Executive Council (as of yesterday), much will be expected of her. The greater federal presence in the bay restoration effort promised by President Obama must be more than symbolic.

Just as the federal Clean Air Act has held states' feet to the fire (forcing Maryland, for instance, to address automobile emissions or lose road construction money), the agency needs to make clear that the Chesapeake states must meet the obligations they've already set for nitrogen, phosphorus and sediment loads in waterways or face similarly drastic action.

To help restore federal credibility, Ms. Jackson should also be willing to take a harder line on overdue enforcement action in the region. In the Baltimore area, that can start with a crackdown on contamination from the Sparrows Point steel mill as required under a 12-year-old consent decree.

Still, environmental advocates and their allies will need to keep pushing the federal government hard, if only to counteract opponents like those at the American Farm Bureau Federation, an influential farming organization that has made killing any expansion of authority under the Clean Water Act a top lobbying priority. Nothing less than the future of Maryland's most important natural resource is at stake.