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Targeted Biomonitoring


The Anne Arundel County Bureau of Watershed Protection and Restoration’s Ecological Assessment & Evaluation Program routinely collects 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.

For stream reaches where restoration work has not occurred, the purpose of this effort is to continue or begin an evaluation of baseline biological conditions before restoration work commences, to understand potential geomorphic (stream channel) instability within the reaches of interest, and to evaluate habitat conditions within the study reaches.

For sites that have already been restored, the purpose of the work is to evaluate any changes in habitat or biological conditions observed in the restored reaches or in reaches immediately up or downstream of restored reaches. The fourteen sampling sites from seven different streams are represented on the map below. 

Sampling Methods and Measures - The sites were assessed using methodologies based on Maryland Biological Stream Survey (MBSS) and WPRP sampling protocols (AAC 2017).  

Two primary measures of biological health were used in this work. The Benthic Index of Biotic Integrity (BIBI) is a multimetric index calculated from a sample of the benthic macroinvertebrates (insects that live in the stream) using procedures developed by the MBSS. The Fish Index of Biotic Integrity (FIBI) is also a multimetric index based upon a sample of the fish population also using methodologies developed by the MBSS.  The kinds and numbers of benthic macroinvertebrates or fish present in a stream, along with other metrics are used to calculate a score between 1-5, with a 1 being a Poor score and a 5 designated as a Good score. 

BIBI/FIBI Score Range
1– 1.99 – Very Poor
2– 2.99 – Poor
3– 3.99 – Fair
4– 5.00 – Good

Fish and macroinvertebrates are a great indicator of stream health because some species are sensitive to disturbances. This sensitivity allows our biologists to assess where issues may exist based on the communities present. For example, some fish are very tolerant of low dissolved oxygen levels while others are extremely sensitive to low dissolved oxygen levels. Looking at biological samples, habitat assessments, and water chemistry samples can provide a good picture of the stream health. Examples of potential problems may include low dissolved oxygen, high sediment concentrations, agricultural or industrial runoff, or lack of habitat. The information gathered can guide watershed partners to restoration or protection efforts.

List of Common Maryland Stream Fishes

List of Common Maryland Stream Macroinvertebrates

Aquatic habitat quality was measured using the U.S. EPA’s Rapid Bioassessment Protocol (RBP) method for low-gradient streams, which is a multimetric visual assessment that scores various habitat features believed critical in supporting high quality biological communities. Most metrics used are scored on a scale of 0 to 20. Those that are scored for each side of the stream are scored from 0 to 10. The individual metric scores are summed and a total score is used to place the reach in a qualitative habitat category. 

RBP Score Range
151 + - Comparable (to reference)
126 - 150 - Supporting (aquatic life uses)
101 - 125 - Partially Supporting
≤100 - Non-Supporting 

Click on a location to learn more about the biological and habitat data for a specific reach.


Sewell Spring Branch (Reference Site) - Consisting of a single site located on Sewell Spring Branch, a tributary to the Severn River, station SR-01 has a drainage area of approximately 574 acres. This site has been nearly continuously monitored since 2005. It is a mostly forested watershed (~60%) and has only about 10% impervious surface, most of which is disconnected. This site was established during geomorphic work performed for another project (Starr et al. 2010) and has become a de facto reference site for the County’s biological monitoring work.

Cypress Creek - There are two stations located in the study area on Cypress Creek, CY-01 and CY-02, both downstream of the crossing at Maryland Route 2. Sampled since 2009, pre- and post-restoration data have been collected at these locations. Both sites are located within the restored reach, where an extensive wetland seepage system was installed in 2013. This is a highly developed watershed and both stations are subjected to runoff from extensive impervious surfaces, with coverage estimated to be approximately 48% for CY-01 and 46% for CY-02.

Dividing Creek - There are two stations located in the study area on Dividing Creek. Sampled since 2010, DC-01 is located just upstream of the crossing under College Parkway while DC-02 is upstream on Anne Arundel Community College property. Implementation of a wetland seepage system in the upstream reach containing DC-02 occurred a few weeks before biological sampling took place in 2016, although the sampling reach containing DC-02 was not directly impacted by the restoration activities. Approximately 27% of each site's drainage area consists of impervious surfaces.

Furnace BranchSampling began in 2016 at two stations in the study area on Furnace Branch. The reach of interest consisted of a concrete channel beginning at a large culvert under New Jersey Avenue, which drains to a natural channel just upstream of Maryland Route 10. FB-01 has approximately 41% of its upstream area as impervious surfaces, while approximately 45% of FB-02 is impervious. Removal and restoration of the concrete channel and restoration of the entire stream channel started in late 2018 and concluded in 2020; therefore, no sampling took place in 2019 or 2020.

Howard's Branch - There are two stations located in the study area on Howard's Branch, bracketing a reach restored in 2000 using a wetland seepage system approach. Sampled since 2007, the data collected are all post-restoration. Impervious surface levels are low, with about 9% found in the drainage area of site HB-01 and about 10% found upstream of HB-02. Typical of the wetland seepage system approach, very large and deep pools are present throughout the restored system making it very difficult to sample using standard County bioassessment techniques because the reach is very deep in some areas. This stream reach was retired in 2020. 

Mill Creek - There are four stations located in the study area on Mill Creek . Sampled since 2010, MC-01 is located at the downstream end of the watershed north of College Parkway while sites MC-02, MC-03, and MC-04 are found in the headwaters to the south of College Parkway. Impervious surface levels range from 17% at MC-04 to 23% at MC-01, but an extensive forested riparian area buffer (~70 to 150 feet, depending on watershed location) exists along this stream between the upstream and downstream sites. No restoration has occurred along these sample reaches, but restoration activities are planned to occur within the next few years.

Cat Branch - New to the Long Term Biological Monitoring Program, there is one station located in the study area of Cat Branch along the little Magothy River. CA-01 is located across from Broadneck Park along College Parkway. This site was restored in 2019. 


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