Joel DunnJoel Dunn is the president and CEO of the Chesapeake Conservancy.
Preserving Mount Vernon’s Potomac
Conservation tool takes long-term view of landscape
Stand on Mount Vernon’s back porch and look out across the Potomac River. The nearly unbroken sweep of woods and farm fields is very similar to that which George and Martha Washington would have seen any spring day in the 18th century.
That this beautiful and historic view is nearly intact is no accident. Protecting it required the foresight to recognize the threat that the fast growth in the suburban DC area posed to the view from Mount Vernon, and it took hard work by the Mount Vernon Ladies’ Association and an act of Congress to address it. The solution was Piscataway Park, created specifically to preserve the view from George Washington’s house.
Piscataway Park was established in 1961. It covers 5,000 acres and stretches for 6 miles along the Potomac shore, from Piscataway Creek to historic Marshall Hall. When it began acquiring land, the park, administered by the National Park Service, was a pilot project for the use of easements to protect land from obtrusive urban expansion. But it also protects the site of a prominent Indian settlement that Capt. John Smith visited as he explored the Potomac River and habitat for many songbirds and animals. Plus, it offers public access to the Potomac and to the Capt. John Smith Chesapeake National Historic Trail.
As a means to protect Mount Vernon’s view, Piscataway Park has been a success. Yet it has not ended the threat that continued development poses. An example of how easily the view can be spoiled exists. A little more than 6 miles away, across the Potomac and up Piscataway Creek, is a development called The Preserve at Piscataway, begun in 2010. It is easily visible and one of the very few modern structures seen from the historic home. It is a perfect example of an ill that new viewshed analysis and viewshed conservation could have prevented.
Recently, the Chesapeake Conservancy worked with the Mount Vernon Ladies’ Association (the oldest conservation organization in the United States) to build a geographic information system that allows anyone with a web browser to see how a proposed building might intrude on the view from Mount Vernon. The tool added new technologies to previous work conducted by Prince George’s County and the Maryland-National Capital Park and Planning Commission. It can show how much and what part of a building would be seen from Mount Vernon and which trees are important to screen the proposed structure from view. This information provides county development officials with previously unattainable details that can help them and the developer site a building in a way that it will not spoil the view.
It also shows conservationists the properties with the highest priority for conservation; for example, those that have the tallest trees to screen distant development, or those that are most likely to be developed and seen from Mount Vernon.
The technical magic of this new tool is based on the ability to map data in great detail, something the Chesapeake Conservancy is perfecting through its Conservation Innovation Center. The Conservancy calls this Precision Conservation. It is based on high-resolution data gathered from satellites and airplane-imaging systems that is precision-located through GPS. It can be used for many things, such as helping a landowner spot exactly where to plant trees to help control pollution from a property, or which lands have the highest conservation value, based on a mix of factors, such as the trees, water, topography and even history.
In the case of Mount Vernon, one essential ingredient in the tool is LIDAR, or Light Detection and Ranging, to generate detailed, three-dimensional information about the land’s topography and surface characteristics — such as the heights of trees. It uses light — a pulsed laser — to measure distances and GPS to note exactly where they are recorded.
The Mount Vernon story captures so much about why it is important to conserve our Chesapeake landscapes. It illustrates the importance of two invaluable conservation tools: easements to protect land and the use of smart planning and good tools to find the right places to protect. Many of these places are historic. Even more of them have irreplaceable ecological values. They shelter wildlife and they provide buffers against air pollution, drought, flood and climate change. Equally important, they are places for us to play, and places where we can learn.
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