Mission of the Tregaron Conservancy

The Causeway's south lawn with views of the Cathedral. Photo from the Frances Benjamin Johnston Collection, Library of Congress

The Causeway’s south lawn with views of the Cathedral, ca. 1919. Photo from the Frances Benjamin Johnston Collection, Library of Congress

The mission of the Tregaron Conservancy is to preserve, rehabilitate and maintain Tregaron Estate’s historic landscape that dates back to 1912. With thirteen acres of land in Washington, DC, placed into a conservancy as open green space never to be developed, the Tregaron Conservancy has been cleaning up and stabilizing a severely neglected and deteriorated landscape. The Conservancy is restoring this famous property, following the original maps and plans of Tregaron Estate’s renowned landscape architect Ellen Biddle Shipman, who was commissioned by prominent architect Charles Adams Platt.

Goals of the Tregaron Conservancy

The purpose of our organization is not only to hold the land as open space, but to restore the property to its original landscape and historical designs through the employment of historical consultants, landscape architects and horticulturalists.  In the past, the Friends of Tregaron retained Robinson & Associates for historical research and documentation, and EDAW for landscape architecture services.

Treg CLR CoverIn addition, we have worked with the renowned Patricia O’Donnell of Heritage Landscapes and the Tregaron Conservancy continues to consult with Ms. O’Donnell for her guidance and involvement in the rehabilitation of the Estate.  In 2005, Heritage Landscapes, a nationally and internationally recognized preservation landscape architecture and planning firm, prepared a detailed Cultural Landscape Report (“CLR”) (pdf) for the historic landscape of Tregaron Estate.  The completion of the Cultural Landscape report in 2007 was funded by the Dorothea de Schweinitz Preservation Fund of the National Trust for Historic Preservation.

The Tregaron Cultural Landscape Report serves the valuable purpose of providing a comprehensive study of the landscape of a historically significant property.  This compilation of landscape-focused historical research, period plans, existing conditions documentation, integrity and character assessment, and landscape preservation treatment recommendations provide a sound basis for undertaking preservation treatment, interpretation and management in the future.  With its original sketches, plans, historical photos, aerials, maps, and current condition pictures, the Tregaron Cultural Landscape Report is a tour de force.

Tregaron landscape units as identified in the CLR

Tregaron landscape units as identified in the CLR

The CLR analyzed the landscape and it existing conditions in great detail.  The report concluded that “[t]he overall historic character of a carefully choreographed, highly articulated and well-cared for landscape has also changed to a landscape in biotic release with notable drainage and water management problems and an apparent lack of care and degradation.  In summary, while the historic significance of the landscape is high, the integrity as found today is low.”  (Heritage Landscape’s Tregaron Cultural Landscape Report, December 2005, p. IV.2)

The CLR’s Rehabilitation Plan recommends the following steps:

  • Conservation and repair of all historic stone structures of walls, bridges and steps
  • Reconstruction of wider bridle paths and narrower woodland trails
  • Stabilization and repair of pond edge, pond inlet and outlet, and stream course to include piped sections
  • Woodland renewal work of several types
  • Attention around historic buildings to recapture elements of landscape character and conserve remaining features

The Tregaron Conservancy is dedicated to stopping the deterioration of the historic estate.  The Conservancy will lead a carefully planned and directed campaign of phased actions to repair, stabilize and recapture aspects of this historically significant landscape.

Arborists, horticulturalists, stone masons and landscape firms have prepared and completed many projects since the Tregaron Conservancy began in 2006.  There are so many restoration projects that are needed at Tregaron.  Many proposals are under consideration, but funding is essential.  We will deeply involve the community in this restoration project and we will educate the public in environmental protection and preservation of natural landscaping – in this case nearly 13 acres of woodlands, meadows, streams and wetlands.

Restoration Plans

After more than 50 years of neglect, Tregaron’s landscape was overgrown with invasive species (vines, poison ivy, volunteer trees such as Norway maples, etc.); a multitude of trees had died and fallen throughout the property, blocking all of the bridle trails and paths.  The lily pond was completely filled with sludge and debris; the Macomb Stream was not flowing clearly and the Klingle Stream was clogged and backed up.  Old rhododendrons no longer flowered due to lack of sunlight.  Stone stairs were damaged; many steps and bridges were covered with many feet of dirt and silt.  The woodland looked more like a jungle and the water features were eyesores.  The meadows had been overtaken by encroaching invasive plants and vines.  The paths were largely unusable.  The iconic 250 year-old Twin Oak tree was dead and dangerous.  Walking through Tregaron was risky business.



The Tregaron Conservancy was established in 2006 to rehabilitate the original Platt-Shipman landscape design.  As mentioned above, a comprehensive Cultural Landscape Report has guided the development of long-term restoration plans.  The Conservancy has cleared invasive growth, removed dead trees, restored paths and cleaned streambeds — discovering buried stone stairs and bridges.

The Story of the Restored Lily Pond

The Tregaron Conservancy’s biggest project to date was the restoration of the lily pond.  After receiving three bids, the Conservancy hired Harmony Ponds to rehabilitate the pond (cost = $100,000) and Vaughan Historic Stone Masons to restore the stone edge.  This was a complicated job that took several months:  historic stone caps were carefully removed and saved; sludge and garbage were removed with major heavy equipment.  The base of the pond was cracked and had to be completely resurfaced.  This involved steel rebars to reinforce the bottom and after that, 25 dump trucks full of shotcrete arrived at Tregaron — filling the bottom of the old pond with a new concrete base.  After the base dried, it was covered with an apoxy sealant.  An aeration system was installed, with two water circulators or “bubblers.”  The stone caps were put back in place, with extra replicates added — all by a historic stone mason.  Once finished, 70 aquatic plants were carefully arranged on the bottom and 96,000 gallons of water was added.  Later, school children and summer camp groups added hundreds of goldfish.  Frogs (which led to tadpoles) made their way to the pond.  Every spring, a pair of ducks returns to Tregaron to lay eggs.  The aquatic plants have thrived — beautifying the pond all spring and summer and into the fall.

Read the Cultural Landscape Report

Note that each Part is a pdf download; some files are quite large
Part 1 – Cultural Landscape Report
Part 2 – Cultural Landscape Report

The Cultural Landscape Report’s List of Plans and Photo Sheets:
Part 1 — Platt-Shipman Sketch Plans
Part 2 — Platt-Shipman era vintage photographs with location notations
Part 3 — 1948 aerial photographs with landscape units
Part 4 — Davies Era vintage photographs
Part 5 — 1980 WIS-TLP aerial photographs, 2000 aerial photographs, 2005 aerial photographs
Part 6 — 2005 photographs with location notations
Part 7 — 2005 drawings of existing conditions and features, 2007 Project Areas Plan
Part 8 — Vegetation Management Plan, Illustrations
Part 9 — Illustrations