From chemical spills to smog and ailing bays, the toxic residue of the 20th century could linger on Long Island for decades.
But as those cleanups progress, the region's challenge for the 21st century will be to limit the collective environmental footprint of its 2.8 million residents:
Septic systems foul groundwater with nitrogen. Cars and trucks pump out exhaust that aggravates asthma and could lead to rising seas and warming temperatures. Polluted runoff sweeps over roads and driveways into estuaries that serve as nurseries for marine life.
The future will likely be a balancing act as communities work to preserve recent environmental gains and keep up with stricter regulations expected in the next decade. At the same time, new strategies will target more subtle forms of pollution - the kind everyone produces - that some experts say carry serious environmental consequences for Long Island's land, air and water.
"Historically, there is this idea that there is some big smokestack somewhere to blame," said Bob DeLuca of Group for the East End, a local conservation organization. "But it's the death of 1,000 cuts that we really have to be concerned about. . . . Septics that aren't maintained, fertilizer on our lawns, road runoff into a creek. I have a sense that the bill is going to come due in the next few years."
Long Island's environmental quality has steadily improved in recent decades, thanks to laws that limit the worst pollution from factories, power plants and other industrial sources.
But long-standing suburban issues remain unsolved. Where will Long Island put its garbage? How can it protect wetlands and preserve open space? At the same time, the region must prepare for long-term threats - such as climate change - while seeking ways to limit chronic, low-level pollution that degrades local air and water.
Among the challenges:
Three-quarters of Suffolk still relies on septic systems, many of which leach harmful nitrogen into bays and underground aquifers that supply drinking water.
Long Island residents produce 22 percent more trash per capita each day than the statewide average.
Fertilizer that keeps lawns green can foul water and feed toxic algae blooms. Polluted runoff has landed 43 local bays and lakes on the state's impaired waters list.
More than half the local emissions that cause smog come from cars and trucks; traffic on the Long Island Expressway is expected to nearly double in the next 25 years, according to state figures.
Tackling those challenges will take a combination of government action and personal choices. Most experts say we will need to drive less, recycle more and keep our septic systems working properly.
"It's the pollution that we cause," said John Turner, director of Brookhaven Town's division of environmental protection. "If we're going to successfully protect Long Island, we're going to have to do it one household and one family at a time."
'Opportunity to reimagine'
For some, the way forward is to change suburban life so we consume less and generate less waste. That could mean taking public transit, carpooling or switching to a low-emission vehicle.
At home, residents could landscape with native plants, start backyard compost heaps, or limit use of fertilizers and pesticides that can end up in local groundwater.
"We can't control what's blowing in from the Midwest, but can we change the habits in our houses and the choices we make with our vehicles," said Carrie Meek Gallagher, Suffolk County's commissioner for energy and the environment.
Others want to retrofit the region. One idea: Instead of building residential developments on virgin ground, recycle old industrial sites near the railroad or underused commercial properties such as Long Island's shuttered auto dealerships located along bus lines. "It's an opportunity to reimagine a place," said Sarah Lansdale of Sustainable Long Island.
To tackle runoff, local governments are looking to modify roads and storm sewers that direct water away from buildings but also serve as conduits for contaminants that close beaches and shut shellfish beds.
Pavement and asphalt cover nearly 30 percent of Long Island - an impervious girdle that prevents the ground from absorbing excess rain and snow. Instead, runoff picks up fertilizer, motor oil and other pollutants and dumps them into streams and bays.
At a boat ramp in Southold, artist and environmental activist Lillian Ball used $80,000 in federal grants and community donations for a unique project to treat storm water that washes into Mattituck Creek. She installed sparkling permeable pavement made of recycled glass that lets water move through to the soil beneath. Plants in a vegetated swale at the water's edge suck up nitrogen and phosphorus.
"When there are torrential rains, they are absorbed by the pavement, the bioswale fills up and waters the plants very nicely," said Ball, a Southold resident who wants to inspire others to follow suit. "There are signs telling people they can have permeable pavement in their driveway, or do a rain garden in their own backyard."
The federal Environmental Protection Agency has encouraged use of rain gardens and permeable pavement; researchers are testing their long-term effectiveness at an agency parking lot in Edison, N.J.
Nassau County has already spent $15.4 million on a range of storm water solutions, from absorbent pillows that sop up oil in catch basins to shoreline plantings that act like wetlands to suck up contaminants. Suffolk and a number of towns and villages have filtration projects, and more are in the works.
Short on funds
As communities experiment with new ways to limit pollution, some warn that environmental gains from previous decades could slip away without renewed investment.
Landmark environmental laws enacted in the 1970s and '80s, for example, have helped preserve wetlands and cut down new toxic waste sites. But at the state level, environmental spending cuts amid this year's budget crisis have advocates worried that enforcement of existing conservation laws will erode - along with state support for open space preservation.
"Right now, Brookhaven and the five East End towns look and function very differently than the rest of the Island," said Richard Amper, executive director of the Long Island Pine Barrens Society. "If we don't preserve more open space and farmland, that distinction is going to be lost."
Money is tight all over. The aging sewage and water plants that have long served as Long Island's first line of environmental defense are due for costly upgrades, and the federal grants that largely paid for their construction dried up years ago. Everyday maintenance and repair remain concerns even at big, well-funded plants such as Nassau's Cedar Creek facility, recently cited by the state labor board for 26 safety violations.
In largely unsewered Suffolk, some are calling for new sewer lines to spur development and prevent pollution from leaky cesspools in older, more densely developed areas such as Mastic that were built before the county's 1981 sanitary code. Suffolk County health department tests found that over the past 20 years, nitrogen levels had increased in all three aquifers that supply drinking water; nitrogen can sicken babies who drink contaminated water.
But laying new pipes could be expensive without significant outside help. In the meantime, Kevin McAllister of Peconic Baykeeper and other environmental advocates want the county to address the problem of outdated septic systems and consider new technologies that reduce nitrogen.
While Suffolk is considering some changes to septic regulations, officials say it might be cheaper to limit other sources of nitrogen such as fertilizer use.
More protection predicted
All the while, federal regulators are expected to keep moving the environmental goalposts. In the next year or so, tighter standards for smog will test Long Island, which already fails to meet federal air quality standards - in part due to pollution that floats in from Midwestern power plants.
New rules and laws are also expected on looming issues such as climate change, declining ocean fish stocks and where to site offshore energy projects.
"There will be more licensing, more regulation and more spatial restrictions in terms of what you can do and where things can go in the ocean," said David Conover, dean and director of the Marine Sciences Research Center at Stony Brook University.
Many of the new rules in coming decades, both locally and regionally, will likely reflect a more holistic approach that seeks to protect ecosystems and public health from the cumulative impacts of human activity.
"You think what you put on your lawn in Nassau County is not affecting water quality in Long Island Sound, but it certainly is," said Judith Enck, regional administrator for the EPA. "It's all connected."