Impact from watershed’s population growth may overtake gains in Bay cleanup
Efforts to control nutrients, sediment will need to be stepped up to offset increased loads from sewage, impervious surfaces
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The Chesapeake Bay watershed population is growing significantly faster than a decade ago, according to new U.S. Census Bureau data—a finding that means states in the region may need to undertake even greater nutrient and sediment control actions to meet Bay cleanup goals.
A new analysis of census data shows that from 2000 through 2005, the population within the the watershed increased by 170,000 per year—or about 466 people every day.
That’s significantly higher than the growth rate of 124,000 people per year that existed during the 1990s. The overall population in the watershed hit 16.6 million last year, according to the analysis.
More people generally means more nutrients going to septic systems or wastewater treatment plants; more runoff from roads, driveways, rooftops and other impervious surfaces; and more air pollution as people drive farther—all factors that degrade Bay water quality.
“Population growth in the watershed challenges our ability to restore and maintain the health of the Chesapeake Bay,” said Peter Claggett, a scientist with the U.S. Geological Survey who made the analysis for the state-federal Bay Program.
“It is a big challenge because we are trying to improve water quality conditions over what they are now, and yet population growth and all the associated land changes that come with that threatens to impede our progress,” he said.
Virginia had the greatest population increase, growing by 447,959 people from 2000 through 2005. Almost all of the state’s growth took place in the Bay watershed, and was led by Loudoun County, the second-fastest growing county in the nation, which gained 81,555 people, a 46.9 percent increase.
An analysis by the University of Virginia’s Weldon Cooper Center for Public Service states that about 46 percent of the growth came from births; the rest from people moving into the state.
Meanwhile, Maryland’s portion of the Bay watershed grew by 286,536 people, Pennsylvania’s 72,336, West Virginia’s 26,936, the District of Columbia’s 10,993 and Delaware’s 9,794. According to the census data, the number of people living in New York’s portion of the watershed decreased by 3,454.
More people are on the way: About 16,000 military jobs are being shifted to Maryland in coming years because of bases closing elsewhere. State officials expect that to trigger the movement of military contractors and other support businesses, resulting in a total job growth of 60,000.
Accelerated population growth could make it more difficult to meet the Bay Program’s 2010 cleanup goal.
The Bay Program in 2003 set nutrient and sediment reduction goals, which were divided among all the states and tributaries in the Bay watershed. The states then developed “tributary strategies” that outlined how they would achieve those goals by 2010. The strategies were also designed to offset additional growth expected through 2010.
Faster growth means that more nutrient reductions would be needed to offset the additional impacts.
“It will essentially steepen the curve to make up for additional population that we hadn’t projected earlier,” said Rich Batiuk, associate director for science with the EPA’s Bay Program Office. “In other words, you have to run faster just to keep up with the population.”
It’s one of the factors that will be explored during an ongoing review by the EPA and the states in the Bay watershed of the existing cleanup goals, and whether they will be achieved through existing tributary strategies.
The issue of growth may be even more acute in the future.
That’s because the nutrient and sediment goals set for 2010 are considered an absolute “cap” on the amount of those pollutants that can enter the Bay and still maintain water quality that supports its diverse fish and shellfish populations, as well as their habitats.
Once the nutrient and sediment goals are achieved, all nutrients associated with more people moving into the watershed—or any additional source of nutrients—has to be offset with further reductions to maintain the cap.
For some places, such as New York’s portion of the watershed where the population is declining, that will not be a major issue. But the job could be far more daunting for areas where the rate of growth is rapid, such as the Washington suburbs in Maryland and Virginia, southern Pennsylvania, West Virginia and Delaware.
To come to grips with those issues, the Bay Program is in the early stages of developing a series of projections about the impact that population growth and other factors—such as changes in agriculture and other land uses—will have on the Bay through 2030.
“We need to understand how much ‘push back’ are we going to get from increased population and other factors,” Batiuk said. “Does that make us think differently about how the tributary strategies continue to be implemented or the kind of policies that need to be there?”
The analysis will explore how different land use policies, and other variables, will affect the region’s ability to maintain the caps. Officials say there is little they can do about population growth, but that policies can affect the impact of additional people on the watershed and the Bay.
“This is the time that we have to be masters of our own destiny,” said Carin Bisland, associate director for ecosystem management with the EPA’s Bay Program Office. “We are not going to put gates around the watershed, but we have an opportunity to influence how people make decisions about where they go and how much space they take up.”
Increasingly, growth is taking place farther from core metropolitan areas, a trend that began in the late 1980s and early 1990s. The trend is illustrated by Virginia’s Loudoun County, on the western edge of the Washington, D.C., metropolitan area. A rural area only a couple of decades ago, it is the fastest growing county in the watershed and is the second-fastest growing county in the nation.
The latest figures show a spike in the growth rate of even more distant areas: Some of the fastest rates of growth in the watershed are coming in the West Virginia and Delaware portions of the watershed, where the populations have increased 11.6 percent and 11.3 percent respectively since 2000.
Doing a better job of projecting where population growth is likely to take place can help provide a heads-up to planners in those areas, Bisland said.
“A lot of the counties that are going to be experiencing the highest rates of growth do not have the capacity, or the staff, to deal with the issues that a high rate of growth has,” Bisland said.
By projecting where that will take place, she said, states may be able find ways to provide assistance to those areas before they are overwhelmed. “It is not trying to take power away from the localities,” she said, “but it is actually giving assistance to localities where you are going to see most of the growth occurring that have the least capacity to deal with it.”
Where those people go can make a huge impact on the Bay.
A recent report on Chesapeake Watershed forests estimated that 5.5 million acres of forest in the watershed are vulnerable to development. Forests absorb more nitrogen than any other land use, so if those woodlands were lost, it would result in an additional 30 million pounds of nitrogen reaching the Bay each year, according to computer model estimates. That would more than offset the 17.5 million-pound-a-year reduction that will be achieved by upgrading all major wastewater treatment plants in the watershed.
Bay Program figures show that if homes are built on septic systems in rural areas, each new person results in about 3.7 pounds of nitrogen entering the local stream. If the home is hooked to a state-of-the-art wastewater treatment plant, that can be reduced to 1.6 pounds per person.
In the 1990s, while the population grew by only 8 percent, the amount of impervious surfaces in the watershed grew by 41 percent as development sprawled over more land, triggering the construction of new roads and shopping centers. Because of such growth, Bay Program figures show that stormwater controls are failing to offset the nutrient impacts associated with new development.
The new Bay Program effort is not the first attempt to project the impact of growth and development through 2030, but it provides more spacially specific growth and land consumption information than has previously been developed.
In 2003, a report by the Bay Program’s Scientific and Technical Advisory Committee, “Chesapeake Futures,” warned that if current development patterns continued, nitrogen and phosphorus inputs to the estuary from new developments would likely offset much of the recent nutrient control efforts. The report estimated that nitrogen loads to the Bay caused by new development and population growth could increase by 35 million pounds per year by 2030, while phosphorus loads could increase by 1.8 million pounds if current development patterns continue.
Under current trends, the report estimated that more than 2 million acres of land would be developed by 2030 to accommodate the increasing population. That would be a 60 percent increase in developed land in the watershed.
Sediment loads would increase as land is disturbed for construction. Each new household will likely consume more than an acre of land based on both the housing construction and the development of support services, such as highways, schools and parking lots.
More sprawl development means more impervious surfaces and therefore, increased runoff. It also means new homes are more likely to have septic systems, which usually are ineffective at removing nitrogen, rather than being hooked into sewer systems.
Alternatively, the report said that those impacts could be reduced if growth management programs were implemented to protect agricultural and forest lands, promote redevelopment and steer new development to areas where most new homes could be hooked to sewer systems.
Under such a scenario, the report said new development might consume just 350,000 acres by 2030, and nitrogen loads to the Bay might increase by just 8 million pounds a year.
Donald Boesch, president of the University of Maryland Center for Environmental Science and an author of “Cheapeake Futures,” said some actions—such as new limits on wastewater discharges that are being imposed by state and federal agencies—will help to prevent the high-end nutrient increases described in the report.
But less progress has been made in other areas, such as managing land use, he said. Nonetheless, Boesch said he was pleased that the Bay Program was attempting to assess long-range implications of policy decisions being made today.
“I’m really glad they’re doing it,” Boesch said of the Bay Program effort. “The program has been so focused on the short term that they have not thought about the long term. This is the way that we need to be thinking.”
About Pollution Caps
In 2003, the Bay Program estimated the maximum amount of nitrogen, phosphorus and sediment that could enter the Chesapeake during an “average” rainfall year and still attain the water quality standards that establish conditions needed to support Bay life.
Once achieved, those numbers become pollution “caps” that must be maintained in the future. Baywide, those caps are:
- 175.1 million pounds of nitrogen (2004 levels were estimated at 270 million, down from 337 million in 1985.)
- 12.1 million pounds of phosphorus (2004 levels were estimated at 18.7 million pounds, down from 27.1 million in 1985.)
- 4.15 million tons of sediment (2004 levels were estimated at 4.9 million tons, down from 5.83 million tons in 1985.)
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