More than 250 scientists, environmentalists, activists and policy makers attended the Washington, DC, event, and they wanted to hear how the EPA planned to withstand the legal challenges that are surely coming in the face of the most comprehensive Chesapeake Bay cleanup plan ever attempted.

Environmental activists have long anticipated the Total Maximum Daily Load, also known as the "pollution diet." They have maintained that states need clear limits on how much pollution can enter each of the Bay's 92 designated waterways and should face clear consequences if they exceed their limits.

Farmers, wastewater-treatment operators and stormwater authorities have been just as adamant that such strict pollution limits will put them out of business. Already, the American Farm Bureau has filed a notice of intent to file a suit. Stormwater authorities in Virginia have indicated they might challenge the state's authority to implement a Watershed Implementation Plan, which is the blueprint each state will follow to achieve the necessary reductions.

"We've been arguing forever, what good is a TMDL if it's not implemented?" said Potomac Riverkeeper Ed Merrifield, who said that he attended the conference specifically to hear EPA officials talk about how they will handle the coming legal challenges.

Some of Merrifield's questions were answered the first day, in a session called "Legal Issues relating to TMDLs," a standing-room-only discussion with agency attorneys and scientists as well as other legal experts. Later in the afternoon, the whole group heard representatives from various states talk about how they were implementing the pollution diet. On the second day of the conference, panelists from different states discussed how local groups could influence the watershed implementation plans.

Ridgway Hall, a former EPA assistant general counsel for water who is now in private practice, gave a history of the TMDL's place in the Clean Water Act and made a case that the agency's authority to implement it is backed by solid statutes. Indeed, several places in the watershed do have TMDLs, but they are not implemented.

"Most TMDLs sit on the shelf," said Rick Parrish of the Southern Environmental Law Center. "Virginia has a law that TMDLs need to be implemented. But the EPA itself does not have such a requirement. So, that's why the watershed implementation plans are so important."

While Parrish acknowledged the current TMDL isn't perfect, he said he doubted that this one will sit on the shelf. In the past, at least 35 groups have taken action against EPA for ignoring its TMDL authority. They and the rest of the public will be watching to make sure that doesn't happen again.

Chesapeake Bay Foundation attorney Jon Mueller agreed with Parrish that the WIPs are the teeth in the TMDL. Mueller and CBF, along with several other organizations, sued the EPA a year ago for failing to come up with a timetable to implement the TMDL.

"In the past, they sat on the shelf because no one required them to do an implementation plan," said Mueller, who settled with the EPA recently.

Mueller isn't surprised about the Farm Bureau's suit, and said one or two other big groups, such as homebuilders or wastewater plants, may also file. What happens, he said, will be interesting.

"All the other TMDLs in the past have been upheld. But there's never been a TMDL like this one-the size, the model, the state implementation plans all make it different," Mueller said.

The TMDLs were a main topic of conversation, but they weren't the only issue on the agenda. Several watershed groups are pushing for a stormwater authority to tackle runoff from rainfall in antiquated urban systems. This runoff is a major source of Bay pollution and is increasing. Stormwater retrofits are expensive, though, and there is sure to be a push back from cash-strapped states if they are asked to spend even more to help the environment.

Like last year, the conference included a session on Marcellus Shale drilling, which the Chesapeake Bay Foundation recently declared to be one of the biggest threats to clean water. Much of the drilling region is in the Susquehanna watershed. State agencies have reported fish kills, water laced with methane and major fragmentation of Pennsylvania's forests.

Other sessions focused on the cleanup of the Anacostia River, green roofs in the District and how to communicate strategies for environmental campaigns.

The keynote talk advised groups to hammer home the message that clean water creates jobs, and pollution costs jobs.

The Choose Clean Water Coalition includes more than 160 organizations from the six watershed states and the District of Columbia who are pushing for federal and local legislation to clean up the Bay's waterways.

The conference organizers had hoped the gathering would be a time to celebrate the Chesapeake Clean Water and Ecosystem Restoration Act, which at times seemed close to passing in the last Congress. The bill, sponsored by U.S. Rep. Elijah Cummings, D-MD, and U.S. Sen. Ben Cardin, D-MD, would have provided more funding for states to implement stormwater controls and, at least in early versions, provided a legal backstop for the TMDL.

Although the bill failed to pass, all was not lost, according to Choose Clean Water Coalition manager Hilary Harp Falk. The push for the bill led to many conversations with newly engaged activists, spurred dozens more groups to join the coalition and laid the groundwork to try again in the future.

But Cummings warned the group that the fight would be hard. He said the new Republican-controlled Congress is unlikely to consider new environmental regulations, and will likely to try to roll back ones already on the books. Still, he urged the group not to wallow in a "pity party," and to keep their eyes on the goal and their head in the game.

"Ladies and gentlemen, I am tired of mourning what could have been. We must realize we have the power to make it what we want to make it," he said. "We have to be up for this fight, and it is a very serious fight. We're fighting for our environment, we're fighting not just for ourselves but for generations yet unborn."