Long-Term Targeted Biomonitoring

The Ecological Assessment & Evaluation Program routinely collects biological, habitat, and geomorphological data from local streams as part of a long term targeted biological monitoring program.

Targeted Biomonitoring in streams


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. 

The sites were assessed using methodologies based on the Maryland Biological Stream Survey (MBSS) and BWPR Sampling Protocols (AACo 2023). 

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. Benthic macroinvertebrates are sampled annually. 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. Fish are sampled every other year to protect the fish population from frequent collection and handling. 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 indicators 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 in 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 

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 monitored since 2005. It is a mostly forested watershed (~55%) with approximately 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.

Cat Branch - A single monitoring site, CA-01, was established on Cat Branch in 2016.  The site is located on the east side of College Parkway, directly across from Broadneck Park.  The site was first sampled for stream macroinvertebrates in 2016 before the start of construction on a stream restoration project.  Construction was completed in 2019 and sampling resumed the following year in 2020. Impervious surfaces account for approximately 28% of the drainage area.

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 50% for CY-02. In 2019, beavers were observed in the area, causing biological sampling of CY-01 to be discontinued.

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 occurred a few weeks before biological sampling took place in 2016. Although DC-02 is within the restored reach, the site was not directly impacted by the restoration activities. Approximately 27% of each site's drainage area consists of impervious surfaces.

Ferndale Branch - FD-01 is located on Ferndale Branch north of Penrod Court in Glen Burnie, approximately 800 ft upstream of the confluence with Sawmill Creek. The site was sampled between 2017 and 2021 as part of a separate study of the Sawmill Creek watershed.  With a stream restoration project set to break ground in 2022, the site was added to the targeted monitoring program in 2021. The site is located in a highly developed area, with 34 percent of the site’s drainage area being impervious surfaces. Construction of an extensive stream restoration project upstream of FD-01 began in early 2023.

Furnace Branch - Sampling 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 drained to a natural channel just upstream of Maryland Route 10. FB-01 has approximately 48% of its upstream area as impervious surfaces, while approximately 54% of FB-02 is impervious. Removal of the concrete channel and restoration of the stream system 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 between 2007 and 2019, 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 from the Targeted Program in 2020. 

Irving Branch - Site IB-01 is located on Irving Branch just upstream of the road crossing at Dorsey Road. IB-01 was sampled between 2017 and 2021 as part of a separate study of the Sawmill Creek watershed.  With a project to restore nearly the entire stream anticipated to break ground in 2023, the site was added to the targeted monitoring program in 2022. Impervious surface accounts for nearly 25 percent of land use within the site’s drainage area.

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 20% at MC-04 to approximately 27% at MC-01, but an extensive forested riparian buffer (~70 to 150 feet, depending on watershed location) exists along this stream between the upstream and downstream sites. MS-01 was restored in 2021 and restoration of the upstream reaches is planned within the next few years.

Muddy Bridge Branch - Two monitoring sites are located on Muddy Bridge Branch in Glen Burnie. MB-01 is located downstream of the 8th Ave road crossing and approximately 300 feet upstream of the confluence with Sawmill Creek.  MB-02 is located approximately one mile upstream of MB-01, directly east of Aviation Boulevard and BWI Airport. Both of these sites are in highly developed areas, and both sites have drainage areas with high percentages of impervious surface - 49 percent in MB-01 and 51 percent in MB-02.  MB-02 lies within the extent of a former stream restoration project completed in the early 1990s by the State of Maryland that has since failed.  With a second restoration project planned at MB-02 in the near future, both sites were added to the targeted monitoring program in 2022. Both sites were monitored continuously between 2017 and 2021 as part of a separate study of the Sawmill Creek watershed.


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