Managing growth remains one of the biggest headwinds to Chesapeake Bay cleanup efforts as the number of people calling its watershed home has increased from about 8 million in the 1950s to about 18 million today.

By 2035, Maryland alone could develop an area of land equivalent to nine District of Columbias, according to state estimates.

Stormwater runoff from developed lands is one of the few sources of Bay pollution still increasing. The amount of nitrogen from stormwater has grown 1.2 million pounds since 2009 to 40.9 million pounds last year, according to recent figures.

The 2016 Chesapeake Bay Summit, which aired April 27 on Maryland Public Television, featured a panel of longtime Bay observers to present ideas about how the region could grapple with more people, more impervious surfaces — roads, parking lots and roofs — and few forests. The program, created in association with the Bay Journal, was also broadcast on a number of other public television stations throughout the watershed.

Ideas included capping the amount of impervious surfaces, incentivizing growth in places where it would have the least impact, requiring governments to fully account for the costs of growth, and even trying to wean society from the need to grow at all.

Rich Batiuk, associate director for science with the EPA Chesapeake Bay Program, said growth does not mean inevitable harm to the Bay, and that some types of pollution, such as discharges from wastewater treatment plants and nitrogen deposition from air pollution, have decreased dramatically thanks to new regulations and new technologies.

“The Chesapeake has responded to that,” Batiuk said, noting that the Chesapeake has gradually improved since the 1980s despite continued population growth.

Other panelists agreed that new regulations and new pollution-control technologies could help, but only to a point.

Most anticipated air pollution controls are in place, and wastewater treatment plants are approaching the limit of their ability to remove nutrients from their discharges.

“Technology can win the day for a while,” said Tom Horton, a professor of environmental studies at Salisbury University, author of numerous books about the Bay, and Bay Journal columnist. “We have doubled the population and slashed the pollution from that population’s sewage. But it doesn’t end there. We’re getting near the limits of our technology — or our ability to pay.”

Several panelists noted that the conversion of open spaces into new development typically resulted in more pollution and loss of habitats. Numerous studies correlate increasing amounts of impervious surfaces, such as roads and parking lots, with the loss of aquatic life in rivers and streams.

New-generation stormwater controls, which seek to give rainfall a better chance to soak into the ground rather than flow directly into waterways, can help. Most panelists agreed that those techniques typically reduce — but do not eliminate — impacts from development.

But in certain situations, new techniques can indeed reduce pollution.

Karen McJunkin, regional partner and vice president of Elm Street Development, which has created a number of “green” developments in the region, said governments can promote growth and reduce pollution by incentivizing the redevelopment of old sites within existing urban areas.

Those new developments, with state-of-the-art stormwater controls, typically have less impact than the old industrial areas they often replace. But such redevelopment efforts often face more permitting and other challenges than developments on fields or forests.

McJunkin said that there is growing public demand for living in urban areas — especially if governments worked better to promote it — citing a “seismic shift in last five years in where people want to live. Permits on Eastern Shore are down 80 percent since the Great Recession.”

Tim Wheeler, managing editor of the Bay Journal and a longtime environment reporter at the Baltimore Sun, said the region should consider a goal of having a “no net gain” in the amount of impervious surfaces, just as it has a goal of “no net loss” of wetlands.

New impervious surfaces would be offset by removing them in other places. Places like Mattawoman Creek in Southern Maryland, a valuable spawning ground for many migratory fish species, are at the tipping point where additional impervious surfaces would be expected to impact fish and other species, he noted.

“If you’re in a hole and trying to get out, the first thing you want to do is stop digging,” he said.

Dru Schmidt-Perkins, executive director of 1000 Friends of Maryland, said local governments should be required to “do the math” and estimate the true costs of new development on the environment, not just the perceived economic benefits.

“It’s a huge economic engine that we don’t account for in typical accounting out there,” she said. “Maybe we can better have people understand what that loss would be.”

Horton went further, saying that ultimately, the region — and society — needed to envision an economy that is not dependent on continued growth. He noted that studies show that areas with slower rates of growth tend to have less poverty and be more prosperous than those with high-growth rates. “You can prosper without growing,” he said.

“We have got to look at how to build an economy that doesn’t require more paving, cutting trees, filling wetlands and more people,” he said. “That’s the one way we are going to save places like the Bay long term. I would stop pursuing this polite fiction that if we just get a little greener, a little smarter, it will all just work out.”

McJunkin questioned how the region could pay for the Bay cleanup — projected to cost billions of collars — without new growth to foot the bill. “I don’t understand how we are going to fix what has already happened without growth,” she said. “I don’t know how else you are going to pay for it.”

But Horton said such as change would not be like “flicking a switch.”

“This is the work of decades, generations,” he said.

Endless growth, he said, is not sustainable in a watershed and planet with finite resources.

The 2016 Chesapeake Bay Summit may be viewed here.