Stream History in Alexandria
Prior to the establishment of the 1970 federal Clean Water Act, communities, such as Alexandria, allowed streams to be paved over and shifted to make room for development. Streams served as the major way to move sanitary waste out of communities and into the river and serve as a stormwater “pipe” to quickly get stormwater out of our communities during storm events.
Today, the City has a robust sanitary and storm sewer system that constantly operates to move our waste and water which reduces the burden on our local streams. However, the impacts of our past still play a part in the streams we see today. You can easily identify streams that have been worn over time by their severely eroding banks, excess trash and debris, vegetation issues such as undermined trees, exposed rootballs, dead and decaying trees, an abundance of invasive plants or lack of vegetation, and excess silt built up on the stream bed. Stream restorations techniques have evolved over time, there are many different techniques that can be used to address the long-term health and vitality of the stream corridor and ecosystem.
To learn more about natural channel design, click here to watch Elbow Creek: a Case Study in Natural Channel Design.
Watch Chesapeake Bay Magazine's Frogs Return to a Restoration Project to see a video about a stream restoration in Davidsonville, Maryland. The original article was published on October 12, 2020 here.
Learn more about the Chesapeake Bay Program's Recommendations of the Expert Panel to Define Removal Rates for Individual Stream Restoration Projects (2014).
Visit the Stormwater Infrastructure Projects page to learn about Lucky Run, Taylor Run, and Strawberry Run stream restorations. The City is hosting a series of workshops and workgroups to discuss Stream Health Improvements for Taylor Run and Strawberry Run. Follow along to hear from experts and provide feedback on how you want to see the streams be managed.
What is Stream Restoration?
“Stream restoration” is a broad term that describes removing blockages within systems (a destructive log jam or human generated trash) to creating a new stream profile to better handle intense rainfall from climate change induced storms. Streams degrade and require restoration primarily from erosive forces destabilizing the banks. These erosive forces come from rainfall that runs off upstream hard surfaces ("impervious surfaces") like sidewalks, roads, etc., and is often a byproduct of urbanization that negatively impacts water quality. The channel size and flow of a stream is directly related to the watershed that drains into the stream. The size of the watershed, the land use, and soils are some of the determining factors that control the volume and velocity of water flowing through the streams. Stream degradation includes channel erosion, channel incision, and streambank undercutting. Obstructions such as downed trees and dumped materials (trash, concrete, etc) may also impede stream flow and cause jams at culverts and sanitary sewer crossings that are above the streambed. Stream Restoration is one way that developed areas can increase their water quality and improve natural habitat for wildlife and residents.
The Northern Virginia Regional Commission (NVRC) developed a Stream Corridor Restoration fact sheet in June 2020. The 9-page PDF document provides details on stream corridor restorations and provides answers to frequently asked questions such as "Why do local governments do stream corridor restoration?" and "Why don’t we let the stream heal itself naturally?" NVRC also developed a Northern Virginia Stream Corridor Restoration Virtual Tour (external link) story map. The map showcases before and after pictures of stream restoration projects throughout Northern Virginia. There are also several time lapsed videos throughout the story map so you can see the construction methods and process.
Curious to see more before and after photos of stream restoration efforts? Fairfax County stream restoration examples.
Interested to learn more about the stream restoration process? The Natural Resources Conservation Service (NRCS), part of the United States Department of Agriculture (USDA), published the Federal Stream Corridor Restoration Handbook (Revised 8/2001).
Stream Restoration Goals
When developing goals for stream restoration projects, an assessment of the full function of the project should be considered. Common goals for stream restoration projects include public infrastructure protection, stabilizing channel banks, controlling the new hydrologic streamflow regime, removing urban pollutants, improving water quality and enhancing aquatic habitat. To learn more about establishing goals and objective in the stream restoration design process, please see the Chapter 5 of the NRCS Federal Stream Corridor Restoration Handbook (Revised 8/2001).
Stream Assessment Study
The City is committed to maintaining the public infrastructure and stormwater system. Three phases of a Stream Assessment Program has been completed to date. Phase I (2004) of the program involved identifying and mapping of perennial and intermittent streams, defining the intermittent/ephemeral stream interface, and approximate limits of ephemeral streams. Phase II (2008) of the program involved the assessment of fifty-seven stream reaches within the City’s eight local watersheds. Stream condition information was collected for habitat, infrastructure impacts, problem areas, stream characteristics, and geomorphic classification. Phase III (2019) of the stream assessment provided a prioritized list of stream restoration projects. The scope of work included assessing, evaluating, and ranking five potential project sites using a decision matrix with a comprehensive list of criteria to prioritize the projects. The two top ranking projects were segments along Strawberry Run and Taylor Run. Conceptual designs were developed for these two highest-ranking potential project sites. The Strawberry Run and Taylor Run Stream Restoration projects are currently in community outreach phase of the process. Learn more about the community outreach by attending the Stream Health Improvement Workshop.
PHASE III STREAM ASSESSMENT STUDY, FEBRUARY 2019
Due to large file size, this study is made available as separate documents.
Appendix A – Recommendations Maps
Appendix B – Field Forms
Appendix C – Substrate Analysis
Appendix D – Bulk Density Analysis
Appendix E – BANCS Model Worksheets (Holmes Run Outfall and Holmes Run F3/F4, Strawberry Run, Taylor Run, Timber Branch, and Unnamed Tributary to Walleston)
Appendix F – BANCS Maps
Appendix G – Pollutant Removal Summary
Appendix H – Soils Report
Appendix I – Project Decision Matrix Criteria Definitions for Scoring
Appendix J – Project Decision Matrix Results
Appendix K – Strawberry Run Concept Design
Appendix L – Taylor Run Concept Design
Appendix M – JBFNC Outfall Into Holmes Run Concept Design
Appendix N – Raleigh Ave Outfall Into Holmes Run Concept Design
Appendix O – Planning Level Cost Estimates
Appendix P – Fort Williams Park Canopy and Plant Community Inventory Map
Appendix Q – Construction Entrance Exhibits
Appendix R – Public Meeting 12/5/2018 – PowerPoint Presentation
PUBLIC OUTREACH On Stream Assessment Study
- Community Meeting - December 5, 2018
Phase III Stream Assessment Study: Potential Stream Restoration Projects
7:00 pm at Douglas MacArthur Elementary School Library
Stream Restoration Projects
Completed Stream Restoration Projects
Strawberry Run Stream Restoration - Downstream
The developer-led Strawberry Run Stream Restoration project completed in 2010 is located just north of Duke Street for approximately 600 linear feet upstream toward Fort Williams Parkway. Strawberry Run suffered from high velocities as evidenced by the down-cutting creating the vertical side banks and depressed stream bed. There was also a considerable amount of concrete and other debris in the stream creating erosive forces that was removed.
Before (left) and after (right) photos of the 2010 downstream Strawberry Run restoration project.
In April 2021, City Council directed staff to conduct a forensic analysis of this stream restoration project. The analysis determined that the project had failed for multiple reasons, including planform stability, construction issues, streambed rock size, lack of rock toe revetment, and change in typical hydraulic forces due to climate change.
At the June 27, 2022 Environmental Policy Commission meeting, the following presentation and report were presented:
Strawberry Run forensic analysis presentation
Strawberry Run forensic analysis, part 1
Strawberry Run forensic analysis, part 2
Strawberry Run forensic analysis, part 3
Strawberry Run forensic analysis, part 4
Holmes Run / Chambliss Crossing Project
The Chambliss Crossing project along Holmes Run near the Dora Kelly Nature Park incorporated stream restoration and a multi-use stream crossing across Holmes Run. The engineering and design analysis explored alternatives for a crossing and stream bank restoration for the banks between North Chambliss Street and the city limits.
The Design was exceedingly sensitive to community desires and the process engaged the local community.
- No rise in water surface elevation
- Maintained as much of the meadow as possible
- Updated the findings of an existing 2002 site/feasibility study for the Holmes Run Multi-Use Crossing with particular consideration paid to recent flood events
- Included hydrology and hydraulic analysis at a preliminary crossing location to identify and propose stream bank stabilization and restoration options which should also be incorporated into design and construction plans
- Included all environmental assessments and environmental impact statements
- Completed design for a crossing and shared-use path connections to existing trails
- Incorporated streambank stabilization/restoration for the banks between North Chambliss and the city line