Biological Stressor Identification Studies

Biological Stressor Identification Studies

picture of channelization of streamBiological impairments impact aquatic communities; therefore, the biological assemblages (e.g., fish, aquatic insects, algae, periphyton) residing in these communities can be used to assess stream conditions and serve as indicators of good or poor water quality. One common measure of biological integrity is an Index of Biotic Integrity (IBI), it is an integrative expression of site condition across multiple metrics that compares the community structure of biological assemblages in a particular stream to that of a high quality (or reference) stream. An index of biological integrity is often composed of at least seven metrics.

In 2002, Maryland began listing waterbodies as impaired for impacts to biological communities in its Integrated Report of Surface Water Quality (IR).  A biological impairment is the detrimental effect on the biological integrity of a waterbody caused by an impact, anthropogenic and/or natural, that prevents attainment of the State’s non-tidal water quality standards protecting and supporting the capability of self-sustaining aquatic life.

For each watershed listed as impaired on the IR, the State is to either establish a Total Maximum Daily Load (TMDL) of the specified substance that the waterbody can receive without violating water quality standards, or demonstrate via a Water Quality Analysis (WQA) that water quality standards are being met. 

The current methodology used to list watersheds as biologically impaired on the IR uses benthic macroinvertebrate and fish IBIs to indicate that a biological impairment has occurred; however, it does not definitively determine the stressor causing the biological impairment. MDE has developed a Biological Stressor Identification (BSID) analysis that uses a case control, risk-based approach to systematically and objectively determine the predominant causes and sources of degraded biological conditions in impaired watersheds. 

The BSID analysis uses the MDDNR MBSS dataset to evaluate habitat, sediment, water chemistry and source parameters in order to determine the potential stressors and anthropogenic sources impacting biological communities in impaired watersheds.  Maryland’s BSID analyzes three key groups of stressors: water chemistry, instream and riparian habitat and sediment/flow related; as well as five groups of land use sources:  urban, agricultural, barren, anthropogenic and acidic (e.g., acid mine drainage, atmospheric deposition). 

The table below lists BSID studies for impaired watersheds.  For more information on the methodology used to identify biological impairments in the IR, click here. Depending on when the BSID study was conducted, there are two applicable methodologies.  One is the initial version developed in 2009 and the other an updated version in 2014 to include the next round of MBSS data. For more information on TMDLs, click here.   

BSID Report Basin Name

DNR 8-digit Basin Number

TMDL/WQA Available

Aberdeen Proving Ground 02130705
Anacostia River 02140205 Sediment 
Antietam Creek 02140502

Phosphorus 

Back River 02130901 Nutrients 
Baltimore Harbor 02130903

 

Bush River 02130701
Bynum Run 02130704 Sediment 
Cabin John Creek 02140207

Phosphorus

Sediment

Casselman River 05020204
Catoctin Creek 02140305 Phosphorus 
Conococheague Creek 02140504 Sediments
Deep Creek Lake 05020203 Phosphorus
Double Pipe Creek 02140304 Sediment 
Evitts Creek 02141002 Phosphorus
Georges Creek 02141004 pH
Gwynns Falls 02130905

Phosphorus

Sediment

Jones Falls 02130904

Phosphorus

Sediment

Liberty Reservoir 02130907

Phosphorus/Sediment 

Licking Creek 02140506
Little Patuxent River 02131105

Phosphorus

Sediment 

Little Tonoloway Creek 02140509
Loch Raven Reservoir 02130805

Phosphorus/Sediment

Lower Choptank River 02130403   
Lower Gunpowder Falls 02130802 Sediment 
Lower Monocacy River 02140302

Phosphorus

Sediment 

Lower North Branch of the Patapsco River 02130906

Nutrients (WQA)

Sediments 

Lower Pocomoke River 02130202
Lower Wicomico River 02130301
Magothy River 02131001
Marsh Run 02140503
Marshyhope Creek 02130306  
Mattawoman Creek 02140111
Middle Chester River 02130509
Nanticoke River 02130305
Other West Chesapeake Bay 02131005
Patuxent River Lower 02131101
Patuxent River Middle 02131102
Patuxent River Upper 02131104 Sediment 
Piscataway Creek 02140203
Port Tobacco River 02140109
Potomac River, Allegany County 02140508
Potomac River, Lower North Branch 02141001
Potomac River, Montgomery County 02140202

Sediment

Nutrients 

Potomac River, Upper North Branch 02141005 Low pH 
Potomac River, Washington County 02140501

Sediment

Nutrients 

Rock Creek 02140206 Sediment 

Seneca Creek

02140208

Phosphorus

Sediment

South River 02131003
St. Mary's River 02140103
Swan Creek 02130706 Nutrients
Transquaking River 02130308 Nutrients 
Upper Chester River 02130510  
Upper Choptank River 02130404  
Upper Monocacy River 02140303

Nutrients

Sediment

Upper Pocomoke River 02130203

Phosphorus

Sediment 

West River 02131004  
Wills Creek 02141003

Phosphorus

Sediment

Youghiogheny River 05020201

pH

Sediment

 

Other Related Links

​United States Environmental Protection Agency Links

Maryland Department of the Environment Links

​Maryland Department of Natural Resources Links

Contact Information

Please direct questions or comments concerning Maryland's Biological Stressor Identification Studies  to Shirley Kirby at (410) 537-4226.