The lower portion of Four Mile Run, from I-395 at the upstream end to the mouth at National Airport, 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.
In 2000, NVRC teamed with the City of Alexandria and Arlington County to explore the stream's water quality and recreation potentials. A formal study was proposed to assess engineered modifications to the channel to improve water quality without decreasing flood control capacity. U.S. Army Corps of Engineers (USACE) partnered with the team to conduct a feasibility study on an alluvial restoration plan.
U.S. Congressman Moran sought allocation through EPA of $1M for development of the Four Mile Run Master Plan, completed and adopted by City Council in 2006. The plan had significant community support from both Arlington and Alexandria residents.
In 2008, NVRC, Arlington County and Alexandria received a Federal State and Tribal Grant (STAG) matched with local funding for the design and construction of the "Demonstration Project" for stream enhancements from Mt. Vernon Ave to Route-1. Combined, the jurisdictions have approximately $6 million for the project.
Since Hurricane Katrina, the USACE began stricter implementation of policies, realted to flood control structures which effects federal sponsored projects included in the Flood Control and Coastal Emergency Act (PL 84-99).
Restoration plans were revised to meet USACE approval and still maintain the goal of the master plan to naturalize and energize Four Mile Run.