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 and currently focus on comprehensive natural channel design that addresses the long-term health and vitality of the stream and its 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).

Click here to be directed to the Stormwater Infrastructure Projects web page to learn about Lucky Run, Taylor Run, and Strawberry Run stream restorations.

“Stream restoration” is a very broad term that can be as little as removing blockages within systems (a destructive log jam or human generated trash) to redesigning and restructuring a stream within its floodplain.  Stream degradation from increased hard surfaces ("impervious surfaces") like sidewalks, roads, etc., in the watershed 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 landuse, and soils are some of the determining factors.  Increased volume and velocities of stormwater runoff due to increased hard surfaces may lead to channel erosion, channel incision, and streambank undercutting.  Obstructions such as downed trees and dumped materials (trash, concrete, etc) may also impede stream flow.  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 will be updated with our stream corridor restoration projects in Alexandria.

Curious to see more before and after photos of stream restoration efforts? Click here to see several examples from Fairfax County, Virginia.

The basic goal of almost all stream restorations is to improve the health of the system.  The benefits are many, and which benefits result is largely dependent upon the methods or activities that lead to restoration.  Among the benefits are increased dissolved oxygen within the water (better for fish and other critters), increased habitat for aquatic organisms, decreased erosion and thus reduced sediment transport, increased water quality, decreased maintenance activities and more efficient flow through the system.  The City of Alexandria is fortunate in that stream restoration is one of the tools available through the Chesapeake Bay Program to meet state and federal mandates to clean up the Chesapeake Bay.

City streams suffer increased flows with elevated velocities when urbanization occurs. These increased velocities result in erosion of the banks and beds of the stream and negatively impact water quality and stream aesthetics.

The City previously completed Phases I and II of the Stream Assessment Program. Phase I of the program was completed in 2004 and involved the identification and mapping of perennial and intermittent streams, defining the intermittent/ephemeral stream interface and approximate limits of ephemeral streams. Phase II of the program was completed in 2008 and involved the assessment of fifty-seven stream reaches within the City’s eight local watersheds. Information related to stream conditions was collected relating to habitat, infrastructure impacts, problem areas, stream characteristics, and geomorphic classification.  The information from these studies will continue to be used to prioritize streams for restoration.  

Phase III of the stream assessment studies was completed in February 2019 (click here for report and here for the stream assessment ranking matrix) and 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 progress and additional information can be found on the Stormwater Infrastructure Projects web page. 

PHASE III STREAM ASSESSMENT STUDY, FEBRUARY 2019

Due to large file size, this study is made available as separate documents.

Main Body
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
  Presentation

Information on City of Alexandria stream restoration projects can be found on the Stormwater Infrastructure  page, and the following individual project pages:

• Lucky Run Stream Restoration

• Taylor Run Stream Restoration

• Strawberry Run Stream Restoration  

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. 

Restoration Goals

The philosophy of this particular stream restoration was to reconnect the stream with the floodplain and attempt to maintain the sinuosity (the amount of curve in the stream) so as create as great of variety of habitat within the stream and riparian area as possible.  This involved adding cross vanes to roll the water away from the banks centering the flow, control the change in hydraulic grade line, and prevent down-cutting of the channel.   J-hooks were added to direct erosive flows away from the streambank, center the flow, and provide scour pools for fish habitat.  Other components of natural channel employed were using jute matting to stabilize toe and bank slopes – anchored with a variety of pins and willow stakes at the toe.  Willow stakes serve to anchor the matting but moreover to provide a network of natural root systems to anchor the banks in place against erosive flows.

Before (left) and after photos of the 2010 downstream Strawberry Run restoration project.   

The Stream Restoration Plan - Taft Avenue (downstream) is available here. Download the Strawberry Run Restoration presentation . 

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.

Considerations
The Design was exceedingly sensitive to community desires and the process engaged the local community.

Project Goals:

• 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