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Biological Monitoring

About the Biological Monitoring Program:

Anne Arundel County initiated a County-wide Aquatic Biological Monitoring Program (Program) in 2004.  Biological assessments are a highly effective approach to understanding the overall health and quality of streams.  Therefore, biological responses are very useful for indicating changes in overall stream ecosystem health.  In other words, by observing shifts in biological assemblages from their natural conditions we can detect impairment in stream ecosystems.

Biological monitoring, however, is not intended to replace surface water monitoring or physical habitat assessment.  Rather, the Program is designed to augment such assessments.  Combining the results of biological, chemical, and physical habitat assessment provides more comprehensive insight into the potential sources of impairment, allowing for prioritized implementation of more detailed, diagnostic investigations and restoration projects.

The primary goals of the Program are to assess the status of the biological stream resources of Anne Arundel County and to establish a baseline for comparing future assessments, to track the status and trends of the biological stream resources, and to relate them to specific programmatic activities.


The Program is based upon the Maryland Department of Natural Resources’ Maryland Biological Stream Survey, scaled down to a County level.  The program is structured such that all major watersheds of the County are sampled in a 5-year period or Round, using a rotating basin design.  In a rotating basin design, a subset of watershed areas are assessed each year, which rotate annually until the entire County is sampled.  Sampling locations within each subwatershed are pre-determined using a probability-based, stratified random sampling design.  Please review the program design document and other quality assurance documents for additional information that fully document the Program’s design.

Click here to explore Anne Arundel County's Fish Atlas ArcGIS Story Map! Learn about the most and least common fish species found in Anne Arundel County waterways through our Biological Monitoring Program. In 2004, Anne Arundel County began the Countywide Biological Monitoring Program (Program) to better understand the health of the County’s non-tidal streams and rivers and the biological communities they support. In the beginning, only stream insect community health was assessed; however, in 2017, the Program expanded to include the fish community. The sampling work underpinning this Story Map, and the related “An Atlas of the Freshwater Fishes of Anne Arundel County, Maryland” document (which can be found in the "Special Projects" table below), occurred between 2017 and 2021.

Fish Atlas cover

The first 5-year monitoring period, called Round 1, was completed in 2008.  The second 5-year monitoring period, called Round 2, was initiated in 2009 and completed in 2013.   Following the completion of Round 2, an evaluation was performed and significant changes were made to the Program, including the addition of fish sampling.  Round 3 began in 2017 and will be completed in 2021.

The complete collection of annual reports for Rounds 1 and 2, along with the Round 3 reports completed to date, are available for download.  These annual reports summarize results for the sampling year and contain descriptions of the individual watershed areas sampled in that year as well as detailed descriptions of monitoring sites assessed. Additionally, for Rounds 1 and 2, summary reports for all the work done in the Round are also available. These reports analyze conditions across all County watersheds sampled during the Round.

As part of the Biological Monitoring Program, EAE staff routinely collect biological, habitat, and geomorphological data from local streams as part of a long term targeted biological monitoring program. The sample sites are located on reaches where stream restoration activities have occurred or are planned for the future.

Aquatic biological monitoring data are shared between State and County entities to provide a holistic picture of ecosystem health in the County.  Additionally, these data are utilized in the County's Bureau of Watershed Protection & Restoration for assessment of stream health during ongoing watershed studies and for stream restoration assessments.  Countywide biological monitoring data is also shared with the State to demonstrate compliance with the County's NPDES MS-4 Permit requirements.


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