Paved surfaces funneling pollution, sediment into the bay
By E.B. FURGURSON III, Staff Writer
First in a three-part series.
A silt plume spreads into Maynadier Creek from Deep Ditch Branch following a rain storm in 2003
The song is true: They've paved paradise and put up a parking lot.
Water-absorbing woodlands in Anne Arundel County have been replaced by hardened surfaces that gush water and pollutants into our waterways and ruin filtering wetlands.
The resulting volume of water spewing from parking lots, streets, residences, farms and commercial buildings during rainstorms has caused untold damage that would cost at least $400 million to repair.
Multiply that volume over a century of intense development and you find what county residents now confront - eroded gullies, silted streams and clogged waterways where boats once passed with ease.
Storm water, carrying sediment and contaminated by nitrogen, phosphorus and other pollutants, has choked bay grasses, killed once plentiful crabs and oysters and spawned algae blooms that suck life-supporting oxygen from the Chesapeake.
That result was highlighted last week when the Chesapeake Bay Program monitoring revealed nearly a third of the bay is a dead zone, too low in oxygen to support life.
"Historically, we have been unwilling to change the way we design and build structures," said developer Michael Furbish, whose projects have included green roofs and living walls that use plants to absorb indoor pollution. "(We) have tried to manage the resulting problem by building expensive, and doomed-for-failure, infrastructures . . . Culverts, underground pipe systems, retention ponds have merely created expensive upkeep of systems that cannot be scaled to address the ever-growing problem. Now those chickens are coming home to roost."
The boom of the 20th century, especially after World War II, brought large tracts of homes and the roads to access them, then shopping centers and the parking lots to feed them. Every rooftop, driveway or patch of concrete road or parking lot exacerbated the problem.
Those impervious surfaces, so called because they prevent the ground from absorbing rainwater, help create a rush of water that experts call "flashiness," like in flash flood.
A recent study by the Chesapeake Bay Program found impervious surfaces in the entire Chesapeake watershed exploded by more than 40 percent, from 611,017 acres in 1990 to 860,004 acres in 2000.
That's the equivalent of paving an area the size of Anne Arundel County in the past 10 years.
Today, 17 percent of Anne Arundel is covered by impervious surfaces, according to the county's estimates. Many of those surfaces are near the county's rivers or directly on the waterfront.
"And there is a rule of thumb," said Jim Miller, county land-use officer. "Once there is 10 percent impervious surface in a given watershed, then you are no longer able to restore the pristine conditions of the free-flowing parts of the stream. All you can do is mitigate the impacts of that development." Some scientists think hitting 20 percent is the point of no return for a watershed.
Long-term damage
Repairing the hole gouged in Allan Kreider's back yard in Arden on the Severn will take four months and cost $1.2 million.
The project is on the county's list of priority watershed restorations set to begin next year with $450,000 from the county and more from the Chesapeake Bay Trust, state and federal sources.
Mr. Kreider's property is the low spot in the neighborhood, which sits above a stream valley that spills into the Severn River.
There were no drainage pipes in the community, nor any county storm water management regulations in 1972 when Hurricane Agnes hit. Torrents of water from the community's rooftops, roads and driveways tore through the yard and carved a gully in the hillside.
Later, the county installed drainage pipes in the neighborhood that connected to a large pipe erected across the gouge. It ended up making matters worse.
"That pipe failed and it started digging a deeper hole," Mr. Kreider said. He peered over the edge, where 30 feet below crumbled concrete and a broken section of pipe sat in the bottom of the hole.
The valley below, called Cypress Branch, was once thick with Atlantic white cedar trees.
That species was a sign of a healthy, working bog - a natural ecologic filter that once lined the shores of the bay and its tributaries, absorbing sediments that leeched from rain-absorbing forests, before waters washed into the bay.
There are but seven cedars remaining in Cypress Branch. The tall, dead hulks of others lean on the abundance of non-native trees, or lie in the foot-thick sediment washed into the valley on the way to the river.
The planned project will repair the erode hillside with a series of catch basins, then restore Cypress Branch to a functioning bog ecosystem.
'Solution is dilution'
When the county enacted storm water regulations in 1982, the engineering rule was to get storm water off the land, into pipes to carry it away. Where? Into the bay.
In the county's increasingly urban environment, that water, heated by pavement in summer, also carries oil, mercury, antifreeze and other spoils.
"The theory was - the solution to pollution is dilution," said the county's chief environmental engineer, Merril Plait. "We have learned that was a bad idea."
According to the Chesapeake Bay Program, urban storm water is the largest source of targeted pollutants, like nitrogen and phosphorous, dumped into the bay from our area. In the Lower Western Shore Tributary area, stretching from the Patapsco River, through much of the county and then along a sliver of Calvert County, some 54 percent of the phosphorus and 37 percent of nitrogen entering the bay comes from urban runoff.
Sewage plants and septic tanks, the target of recent state legislation, contribute only slightly more nitrogen than rainwater rolling off our roofs, driveways, streets and parking lots.
Now the Environmental Protection Agency is beginning to study the impact of the sediments themselves, outside of the chemicals that hitch a ride with them.
County Soil Conservation District chief Jeff Opel is the only non-scientist on the EPA's Chesapeake Bay Program Sediment Workgroup panel studying that issue. The group is trying to determine how sediment folds into the overall bay strategy.
But he is cautious about labeling all sediment as bad.
"The movement of sediment and exchange of nutrients is crucial for the environment, it is needed," he said. The problem is the amount of sediment and nutrients generated by urban environments is more than the eco-system can take.
"It is out of balance."
Published 07/31/05, Copyright © 2005 The Capital, Annapolis, Md.
Click here to contact your council members in support of a Stormwater Management Enterprise Fund
Click here to go to Part Two in the series.
Here are some contacts to learn more about it:
ø Development and the Bay
ø General Stormwater Management
ø To learn more about watersheds, click here and here
Back to Watershed Restoration Fund Page
