Watershed Retrofit Study
A watershed retrofit is the addition of a stormwater facility to an area that currently doesn’t have one. Adding a stormwater facility can help slow down and filter stormwater runoff before it flows into local streams. This is important in areas like Arlington, where much of the County was developed before stormwater requirements were enacted. One example of a watershed retrofit is a green street.
We worked with the Center for Watershed Protection to develop watershed retrofit plans and a County-wide project inventory. During the process, all of the County’s watersheds were studied to find space where small stormwater facilities can be added. The Watershed Retrofit Study was completed in December 2013. This effort is part of the Stormwater Master Plan.
Prioritizing Retrofits
The sites were scored and prioritized based on several factors:
- Runoff reduction: The capacity to decrease stormwater runoff from the drainage areas they capture.
- Pollutant removal: The capacity to reduce pollutants from the sites they capture.
- Alleviation of drainage problems: The capacity to alleviate existing drainage problems, when feasible.
- Education and outreach: The capacity to provide outdoor learning and community outreach opportunities on public lands, where possible.
- Construction: The ability to construct based on site constraints such as property ownership and utilities.
- Maintenance: Requirements for County maintenance.
Ranked List of Retrofits
Doctor's Branch, Lubber Run, Spout Run and Windy Run

Ranked Listing of Projects
Public Meetings
Donaldson Run, Gulf Branch and Upper Four Mile Run

Ranked Listing of Projects
Note: Torreyson Run, Crossman Run and Westover Branch subwatersheds are are part of the larger Four Mile Run watershed.
Public Meetings
Four Mile Run – Lower Mainstem and Potomac Palisades

Four Mile Run – Upper and Middle Mainstem

Ranked Listing of Projects
- Arlington Forest Branch
- Bailey’s Branch
- Fairlington/Bradlee
- Four Mile Run – Middle Mainstem
- Four Mile Run – Upper Mainstem 1
- Four Mile Run – Upper Mainstem 2
- Lucky Run
- Upper Long Branch
Public Meetings
Little Pimmit Run
