Business leaders, neighborhood activists and schoolchildren recently joined Baltimore Mayor Stephanie Rawlings-Blake in unveiling a plan to clean up Baltimore's Inner Harbor.

The plan calls for major investments in sewage pipes, so that the harbor isn't the victim of more nasty spills that deposit millions of gallons of sewage into the streams leading to it. It also calls for more nets to catch trash, a greater investment in neighborhoods and more infrastructure to soften the blow from stormwater laden with pollutants every time it rains.

The goal is to make the Inner Harbor swimmable and fishable by the year 2020. It is an idea that was once unfathomable, but other cities - notably Boston - have done it. Baltimore leaders say there's no reason they can't also succeed.

"Now is the time to take action and invest in our city's future," Rawlings-Blake told the crowd of about 100, who assembled in the Living Classrooms Foundation's campus on the water in Fell's Point for the announcement. "We must create a cultural shift in our city. Everyone can make a difference for clean water."

Baltimore residents and a few activists have been talking about cleaning up the harbor for decades. The difference now, longtime activist Phil Lee said, is that the business community is behind the effort. Harbor businesses pay a tax - 5 percent of their property tax - to fund the harbor cleanup. The money goes to the Waterfront Partnership of Baltimore, which uses the funds to keep the area around the harbor clean, hold events showcasing the water and invest in long-term cleanup plans.

"When we started eight years ago, it was a lot of effort, but the wrong people were doing it. We were just preaching to the choir," Lee said. "Really, the most important thing now is that it's being done by the movers and the shakers. These are people who are paying attention, that's the big difference."

To know where they were headed, the partnership needed to know where it stood. So, it asked the University of Maryland Center for Environmental Science's Integration and Application Network to conduct a report card for the Harbor. The center does report cards for many other rivers in the Bay, including the Patapsco, but it hadn't done a specific one for the harbor.

The center released the report card at the Fell's Point event. The harbor scored an F for total nitrogen, a D-minus for total phosphorus and a D for its bacteria levels.

Nevertheless, William Dennison, the center's vice president for science applications, said the poor scores were no reason to despair.

"This is the worst, but we knew it would be," he said. "That's what makes it exciting, because if you can raise the worst, we can raise the rest of the Chesapeake Bay. We have a unique public-private partnership here, and they've embraced it. They're not just looking to the government for solutions."