Stream Restoration

Picture of Stream Restoration  

Streams today, as we know them, are not as they used to be. Today one often sees a single channel of water carving gullies throughout floodplains clogged with sediment (from centuries of deforestation). Originally, streams were broad, braided channels spreading through wetlands that filled entire valleys. For more information on Maryland's streams, see "Maryland's ​Streams: Take a Closer Look".​​

Stream restorations are a complex and challenging undertaking. A degraded stream is an unhealthy stream, and an unhealthy stream can also cause adjacent areas of the environment to be unhealthy. Just like a patient who visits his/her doctor with symptoms, an unhealthy stream also has symptoms. For example, water quality can be poor in an unhealthy stream, habitat can be degraded, the aquatic species which should be present may be absent, and the adjacent riparian area and wetlands may also show symptoms of degradation. Healthy streams need healthy adjacent wetlands and vice versa.​

Goals of Stream Restoration


The goals and objectives for any stream restoration project vary. The following list of potential goals and objectives illustrates the many possible goals for stream restoration projects.

  1. Habitat improvement for fish
  2. Preventing streambank erosion (and having sediment entering the water)
  3. Restoring hydrology
  4. Reconnecting the stream to its floodplain and adjacent wetland
  5. Slowing the procession of head-cutting in a watershed to protect upland areas and to reduce sediment and nutrient delivery downstream
  6. Reducing the rates of lateral migration of the stream
  7. Narrowing an overly wide channel to provide a better ratio for aquatic life of depth to width
  8. Improving water quality
  9. Removing nonnative riparian vegetation and replacing it with more desirable species
  10. Maintaining riparian forest buffers as appropriate
  11. Re-establishing a sinuous channel from a channelized reach

The Maryland Department of the Environment, Water and Science Administration,Wetlands and Waterways Protection Program​, reviews proposed projects and issues permits for any activity wh​ich impacts tidal and nontidal wetlands and waterways, including 100-year floodplain. One specific type of activity which is gaining in popularity is ecological enhancement of these regulated resources through stream restoration projects.

The recent increase in the number of stream restoration practices being permitted in the State is due to many factors including water quality restoration goals required by Municipal Separate Storm Sewer System (MS4) permits, the Chesapeake Bay Total Maximum Daily Load (TMDL) Watershed Implementation Plans (WIPs), and local TMDLs. See the following data chart for reference numbers of projects in Maryland:​

​​​​​Calendar Year
​Restoration Permits Issued
​% Issued in 90 Days​​
​Total Stream Length (FT)
​Average Stream Length (FT)

Why Stream Restoration?



Stream Restoration has been recognized by the US EPA Chesapeake Bay Program and the State of Maryland as providing numerous water quality and ecological benefits. The Phase 6 Chesapeake Bay Watershed Model estimates the annual export of nitrogen, phosphorus, and sediment from a stream bed and bank source to the tidal waters of the Chesapeake Bay. This export of pollutants from Maryland’s nontidal streams to the Bay is the result of many different anthropogenic stressors to the State’s nontidal streams and floodplains, over the course of several hundred years. Typical stream restoration techniques aim to stabilize streambeds and banks to prevent erosion and sediment export, promote floodplain reconnection, enhance surface/groundwater interaction, promote nutrient cycling and denitrification, enhance sediment trapping in floodplains, and improve habitat conditions for in-stream aquatic life. Oftentimes, these stream restoration techniques require the diligent removal of existing vegetation, including some trees, and the careful reshaping of the stream itself. During these periods of change, the visual landscape can change greatly. Tracking these restoration projects over time has shown the ecological community to be resilient with new, healthy species being established in a short amount of time (see Pictures section). These techniques generally improve stream hydraulics and as a result reduce nutrient and sediment loads being delivered downstream. Coupled with improved habitat for in-stream aquatic life, stream restoration projects generally result in overall ecological uplift to a system.

There are many degraded urban and suburban streams in Maryland. MDE does not allow restoration projects to be undertaken in a stream unless there is evidence of degradation. That is, the stream must exhibit one or more symptoms of being unhealthy. A common symptom is incising of the stream channel and eroded stream banks along with changes in the aquatic community as well as changes in the plant community in the adjacent riparian area from it being hydrologically disconnected from the stream. This disconnection sometimes results in species of trees growing in the area adjacent to the stream that are not wetland trees. In other words, the whole character of the stream/wetland complex has been changed because the stream is degraded and restoring the stream and re-connecting it to the floodplain will in turn lead to another cycle of changes in the adjacent land ---including the loss of trees that are not adapted to wet conditions associated with the natural periodic out-of-bank flooding. To aid in the transition, planting plans are often requirements of MDE permits and often compelled by compliance with the Forest Conservation Act at the state and local levels. Further stewardship for forest management can be incorporated into a project by engaging Maryland Department of Natural Resource’s Forest Conservation and Management Program.​​

Credits for TMDL Goals and MS4 Permits


Because of many benefits of stream restoration, the US EPA Chesapeake Bay Program Partnership and the State of Maryland allow and encourage local jurisdictions, watershed organizations, and other stakeholders to use stream restoration projects to meet MS4 permit requirements and TMDL goals. MDEfollows guidance from the Chesapeake Bay Programon calculating the nutrient and sediment load reductions, qualifying conditions, and verification procedures for stream restoration through Partnership approved Expert Panel reports. As stream restoration has continued to evolve, the Stream Restoration Expert Panel report has evolved as well. New recommendation memos provide updates to the load reduction calculation methodologies, qualifying conditions, etc. outlined in the original expert panel report, which was published in 2013. These memos are based on consensus from the scientific, regulator, non-profit, and practitioner communities. The original stream restoration expert panel report and subsequent, accompanying memos can be found on the Chesapeake Stormwater Network’s website here:

The recommendations from the following reports were incorporated
Image of the Accounting for WLAs and Impervious Acres Treatedinto MDE’s 2020 MS4 Accounting Guidance, which details how nutrient and sediment load reductions are translated into MS4 permit metrics:

  • Recommendations of the Expert Panel to Define Removal Rates for Individual Stream Restoration Projects, 2013
  • Recommendations for Crediting Outfall and Gully Stabilization Projects in the Chesapeake Bay Watershed, 2019
  • Consensus Recommendations for Improving the Application of the Prevented Sediment Protocol for Urban Stream Restoration Projects Built for Pollutant Removal Credit, 2020
  • Consensus Recommendations to Improve Protocols 2 and 3 for Defining Stream Restoration Pollutant Removal Credits, 2019
  • Recommended Methods to Verify Stream Restoration Practices Built for Pollutant Crediting in the Chesapeake Bay Watershed, 2019​​

Holistic Watershed Restoration


D​espite the many benefits of stream restoration, the Department cautions stakeholders in relying solely on this practice to meet water quality goals. MDE encourages and has incentivized holistic approaches to watershed restoration. This includes a combination of both upland and in-stream practices. Upland practices can include a wide array of practices in rural, urban, and suburban watersheds, but generally speaking they include practices such as stormwater management retrofits, reforestation, tree planting, forested and grass stream buffers, urban soil restoration, cover crops, streamside fencing, and many more. Determining what practices are implemented, where they are implemented, and how many practices are implemented should be determined through a comprehensive watershed planning effort that utilizes an adaptive management framework. As it specifically relates to stream restoration, MDE recommends that the practice should not be implemented without prior consideration to other potential stressors upstream of a given project and after evaluating the individual, ecological benefits and costs of any given project. These considerations are reflected in MDE’s project permitting processes.

Stream restoration and watershed retrofits are both important to protect our water resources. Watershed retrofits are stormwater management features added close to the source to slow down and treat stormwater runoff. Watershed retrofits can help improve water quality in streams, but in urban watersheds, space to construct these features can be limited. Also, watershed retrofits cannot undo the damage that unmanaged stormwater runoff has already caused to local streams. Streams that have eroded down and widened in their channel will continue to do so, washing more sediment and nutrient pollution downstream, and threatening more trees along the stream channel.

Often stream restoration requires removal of the existing upland forest for the purpose of regrowing a floodplain forest. Because of this, stream restoration projects should consider:

  • Forest Management plan to support regrowth of floodplain forest when the existing forest must be removed
  • Considering a transition plan that allows the old forest to die off and be naturally replaced with floodplain forest​



The Department recognizes that these “restorative” projects are fundamentally different from development projects in that their intended result is an overall uplift of ecological function. To that end, the Department instituted several measures to ensure that these projects were reviewed differently than development projects. Specifically: having a dedicated team of permit review staff of 2 engineers and a natural resources planner who only handle restorative projects along with producing guidance documents/checklists for restoration applicants to help ensure a complete application submission. The U.S. Army Corps of Engineers also recognizes the importance of such projects. The Corps has issued the Chesapeake Bay Total Maximum Daily Load Regional General Permit and activated Nationwide Permit #27​to streamline permitting of qualifying projects in Maryland. The Wetlands and Waterways Protection Program has prepared guidance documents for preparing permit applications of MS4/Chesapeake Bay TMDL/Trust Fund and Restoration Projects. Additionally, the Department recognized that restorative projects, many times, require permit modifications during construction. To assist in the timely review/approval of necessary changes, the Department developed a Tiered Approach to modification approval for restoration projects​​.

How the Process Works


Stream restoration "practitioners" generally go through a careful evaluation process prior to applying to MDE for an authorization to undertake a restoration project. This evaluation process typically involves:

    (1) Identifying the problems and the opportunities (that is, determining what the nature of the degradation is and what needs to be changed or fixed).
    (2) Determining the specific goals and objectives for the project (that is, what is the "desired" end state regarding changes in the physical, chemical and/or biological condition of the stream and its adjacent wetland).
    (3) Inventorying the resources present---study the stream to understand the physical processes at play, the impacts on water quality and the abundance and distribution of biological populations and determine what processes most influence the desired stream condition.
    (4) Formulating alternatives--determining which processes can be changed to improve stream health while minimizing disturbances and avoiding unnecessary upheaval.
    (5) Evaluating alternatives---determining which of the alternatives are sustainable, cost effective, and best meet stated goals and objectives while minimizing impacts to the environment.
    (6) Making the decision regarding the stream restoration approach to be implemented. All stream restorations are not created equal as to existing conditions and the need for precise tree removal to access the stream is extremely important.

** Please note MDE is not alone in this effort. Other agencies of federal, local, and county governments are also involved in this teamwork process.



As restoration techniques and their water quality effects continue to evolve,the Department continues to engage with the academic and research community to gain a better understanding of project benefits and shortcomings.Photo of Stream Monitoring
Specifically, ​MDE continues to review the results of permitted project monitoring and work with partner organizations, such as the Chesapeake Bay Trust’s Pooled Monitoring initiative, to guide research studies intended to help us understand the overall effects of stream restoration. The Chesapeake Bay Trust’s pooled monitoring initiative provides critical research in regards to specific watershed restoration techniques, variable elements of those techniques, and watershed restoration as a whole. One of the primary focuses of these research efforts has been stream restoration. A list of the current research projects funded by the initiative and any applicable results and materials can be found at​.​



MDE strives to ensure that there are the least possible adverse impacts to existing, valued resources while achieving the project purpose---which is to improve the functioning of a degraded stream and the stream/wetland complex. Nutrient and sediment management is one of the benefits of stream restoration but typically not the only benefit--restoration of habitat is important as is the re-connection of the stream to its floodplain.

MDE's Wetlands and Waterways Protection Program does its best during the review of applications to ensure these projects are conducted in an ecologically sound manner and done in a manner that avoids and minimizes impacts to other valued resources.

For More Information


For more information about stream restoration projects and permitting, contact:

Wetlands and Waterways Protection Program
Division Chief 410-537-3837

For more information about TMDLs or Credits for TMDL Goals, contact: Watershed Protection, Restoration, and ​Planning Program at

Other Sites

​Example Stream Restoration Projects Permitted by MDE (Before, During, and After)​​

Bear Cabin Branch in Harford County



- Note the incised stream banks eroding sediment into the stream


During Construction:



After Construction: (Approximately two years later).



Furnace Creek in Anne Arundel County – Completed Spring 2020


​​Before/After Aerial Footage:


Gwynn Falls at Kingsbury Stream – Completed Fall 2021



Kingsbury 1 Before 2015-12-02.png

After Construction (Immediately):

Kingsbury 2 After (Immediate) 2021-10-19.png

After Construction (Approximately 1 Year Later):

Kingsbury 3 After (1 year) 2022-08-31.png

Slaughterhouse Run – Completed Fall 2019



Slaughterhouse Manhole Before 5-14-2019.png

After Construction:

Slaughterhouse Manhole After 6-1-2020.png

White Marsh Run at Upton Road – Completed Spring 2019



WMR at Upton Before 3-2015.png

After Construction (Immediate):

WMR at Upton After (Immediate) 5-2019.png

After Construction (Approximately 2 Years Later):

WMR at Upton After (2 Years) Summer 2021.png


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