- January 2016 - The Four Mile Run Park path is now
re-opened for pedestrians and cyclists. The
wetlands trail will be remain closed until spring when there is dry and
predictable weather to complete it. The pink flags will remain in the wetlands
for one year in order to deter geese as plants establish.
tuned for a ribbon ceremony date upon full completion in spring 2016.
Four Mile Run Overview
Four Mile Run is a nine-mile long stream located in a highly urbanized area in
Northern Virginia. Its 19.6 square mile watershed covers portions of Arlington
and Fairfax Counties and the Cities of Alexandria and Falls Church. The lower
portion of Four Mile Run, from I-395 at the upstream end to National Airport at
the mouth, is contained in a hardened flood control channel and marks a rough
boundary between Arlington County and the City of Alexandria. Along this
stretch of Four Mile Run are neighborhoods, commercial districts, and some
industrial facilities, including the Arlington County Water Pollution Control
Plant. Because of the highly urbanized nature of the Four Mile Run watershed,
the neighborhoods and businesses adjacent to this portion of the run were
subjected to repeated flooding, beginning in the 1940s. In response to this
flooding, the municipalities forged a partnership with the US Army Corps of
Engineers (USACE) to build a flood-control channel in the lower portion of Four
Mile Run. Construction of that channel took place during the 1970s and early
1980s. Since its completion over twenty years ago, the channel has safely
conveyed the high storm flows through the two jurisdictions and prevented
Four Mile Run Restoration Project
The restoration project
is a joint venture to restore 2.3 miles of a highly degraded stream within the
hardened flood control channel - or levee corridor - of Four Mile Run. Through
a partnership of efforts and funds, residents and staff from Alexandria, Arlington,
the Northern Virginia Regional Comission (NVRC), the US Environmental
Protection Agency, the US Army Corps of Engineers and Congressman Jim Moran's
office have been working collaboratively to successfully implement the
framework set forth by the Four Mile Run Restoration Master
The Four Mile Run Design Guidelines, as approved by Arlington County and the Alexandria Planning Commission in September 2009, were created to govern the aesthetic and physical components of the stream corridor. The Design Guidelines include recommendations that will guide trails and paths, stream crossing, bridges, lighting, building orientation and setbacks, benches, the proposed Nature Center, and vegetation; among other physical components.
A citizen-led Joint Task
Force (JTF), with representatives appointed by the chief administrative
officers of each jurisdiction, examines project alternatives, gathers public
input, and provides recommendations to the project’s Agency Coordination Group
(ACG). Members of the ACG represent the various local, regional, and federal
government agencies involved in the planning and implementation of the
restoration effort. A list of JTF members and an archive of meeting summaries
are available on the project website.
NVRC is facilitating the
administration of the Four Mile Run Restoration Project and additional
information related to the project can be found on their website.
Tidal Restoration Demonstration Project
The Tidal Restoration Demonstration Project works to restore the banks of the shoreline and wetlands in the channelized portion of Four Mile Run, from Mt. Vernon Avenue to Route 1.
A major objective of the Master Plan is to reestablish the vegetation that once lined the stream and existed in the lowland wetlands areas but has since disappeared or been colonized by invasive species. The Four Mile Run Wetlands Restoration, completed in December 2015, plays a prominent role in regional efforts to protect the Potomac River basin and the endangered Chesapeake Bay by restoring the natural cycles and diversity of habitat to support a variety of life in and along these waterways. The Restoration project restored the historic 2-acre tidal wetland where the water levels fluctuate with the daily tidal cycle along Four Mile Run. Wetlands were once common along all the tidal tributaries and protected shorelines of the Potomac River, but many tidal wetlands have been lost to urban and suburban shoreline development. The upland trail serves as a buffer between the tidal wetland and the existing forested wetland. Wetlands are important to both wildlife and humans and provide a connection between aquatic and terrestrial habitats that is important to fish and aquatic organisms as well as many birds and terrestrial animals. Tidal wetlands are important nurseries and foraging areas for fish, waterfowl and other birds, reptiles and mammals. Wetlands also benefit humans by improving water quality and storing floodwaters.
Tidal wetlands can be divided into different plant zones based on fluctuating water depths. This created wetland includes a low marsh zone and a high marsh zone and is surrounded by an upland meadow.
The low marsh zone is typically flooded for more than ½ of the day by water up to several feet deep. This extensive inundation limits the diversity of plants that can grow in this zone. Common low marsh plants, such as the yellow pond-lily (Nuphar advena) and the arrow arum (Peltandra virginica), provide cover for juvenile and adult fish and other aquatic species. The ten-foot tall, emergent grass, wild rice (Zizania aquatica), was an important food crop for Native Americans and remains an important food source for water fowl. The prolonged and deep inundation by tidal waters allows the low marsh vegetation to take up nutrients and trap sediments from the flood waters.
The high marsh is flooded less than ½ the day by water that is typically less than one-foot deep. The vegetation community is composed of many species that form a dense cover. Grasses, sedges and rushes, such as rice cut grass (Leersia oryzoides), soft rush (Juncus effusus), woolgrass (Scirpus cyperinus) and three-square (Schoenoplectus pungens) are common in the high marsh, as are forbs such as rose mallow (Hibiscus laevis), broadleaf arrowhead (Sagittaria latifolia), and swamp milkweed (Asclepias incarnata). The diverse plant community provides habitat to many insects, amphibians, birds and other animals. The high marsh is not inundated for long periods, but the dense vegetation is efficient at capturing sediments and pollutants from floodwaters.
The upland meadow is a perennial herb community that is not regularly flooded. It provides terrestrial habitat utilized by many of the same species that live in the wetland; frogs forage in the meadow and turtles nest here. A mix of grass species and flowering herbs, such as black-eyed Susan (Rudbeckia hirta) and goldenrods (Solidago spp.), provide foraging and nesting habitat for many song birds and provide nectar and act as larval hosts for native pollinators while providing cover habitat for other wildlife. The meadow vegetation also provides soil stabilization and erosion control.
Four Mile Run Bridge Demolition
Construction on the westernmost bridge between Route 1 and Potomac Avenue is complete. The removal and
subsequent dedication of land is part of the The Four Mile Run Restoration Master Plan, endorsed by the Four Mile Run Joint Task Force
and ultimately adopted by both the Alexandria City Council and the Arlington County Board in 2006. The removal of the bridge is part of a large, ecological plan that provides regional benefits as intended by the Commonwealth’s Chesapeake Bay requirements, the City’s Water Quality Supplement to the City of Alexandria
Master Plan, as well as the
City’s Eco-City Alexandria initiative, and the approved
Eco-City Environmental Charter and
Action Plan. Improving the existing streams and adjacent buffer areas increases the natural light levels within the Run, improving the stream’s natural ability for pollutant removal.
Pedestrian/Cyclist Bridge Competition
The City of Alexandria, Arlington County, in partnership with the Northern Virginia Regional Commission, announced the signing of a contract for the design of the Four Mile Run Pedestrian-Cyclist Bridge based on the March 2010 Bridge Design Competition and Call for Qualifications. This step began the formal design and technical engineering process for this bridge envisioned in the
Four Mile Run Restoration Master Plan.
Since the design competition, Arlington, Alexandria, NVRC and the Virginia Department of Transportation worked to develop the Scope of Services for the design and engineering. Understanding the constraints of the project, timeframe, budget and scope, the 2nd ranked team entered into an agreement for design services. The jurisdictions began the design process with Buro Happold and member of the second ranked team of Olin/Buro Happold/Explorations Architecture/ L’Observatoire International. A presentation of their work and the competition renderings of their concept can be viewed on the