Prince George's County

Biological Monitoring

Biological monitoring is used to evaluate the health of a waterbody using resident aquatic macroinvertebrates as indicators of stream health. Benthic macroinvertebrates are a diverse group of small, bottom-dwelling aquatic organisms without backbones that can be seen with the naked eye. Because benthic macroinvertebrates spend most of their lives in one area within a waterbody, they are widely used as effective indicators of waterbody health through routine sampling and analysis. The presence, or lack thereof, of pollutant-sensitive macroinvertebrates is considered a good indicator of stream health.

Prince George’s County (the County’s) biological monitoring and assessment program seeks to address three goals:

  1. Generate reliable data to answer questions about the current health and long-term trends of local waterbodies.
  2. Identify water quality issues by documenting stressors, their sources, and any interconnectedness among them.
  3. Assess the success of environmental management and restoration efforts to inform future decision-making.

The County maintains a longstanding biological monitoring and assessment program. Implemented in the 1990s, the program involves sampling streams and small rivers within the County’s 500 square miles. To date, the County has performed five rounds of countywide biological monitoring, with 1,240 samples taken from 1,146 sites. The program previously used a random site selection process, which resulted in a similar proportion of sites being sampled in 41 subwatersheds, usually totaling around 250 sites each round of sampling. In the future, the Maryland Department of the Environment (MDE) has directed the County to obtain samples from each watershed in the County every year including habitat data. In response to MDE requests, the County has partially revised the design of its biological monitoring program so that now a subset of subwatersheds will be sampled and assessed annually.

The County uses the Maryland Department of Natural Resources’ (DNR’s) benthic index of biological integrity (B-IBI) as its principal indicator of stream conditions. Field teams follow DNR’s Maryland Biological Stream Survey (MBSS) protocol to evaluate sites using biological indicators. This protocol includes assessing physical habitat quality, collecting field chemistry (e.g., pH, conductivity, temperature, dissolved oxygen), and collecting benthic macroinvertebrates. Each year, the County shares its biological data with DNR and MDE for incorporation into the State’s Integrated Report of Surface Water Quality in Maryland.

Dashboard Instructions 

Features

  • Use the filter bar, located at the top right of the screen, to refine data based on water quality constituent(s), subwatershed(s), and year(s) collected. Upon clicking the themed filter box, select one or more option from the drop-down menu. Data displayed in the map and tables will then update based on selection. Please note:
    • Filters from multiple themes can be selected at the same time. 
    • Due to the nature of the datasets, biological and stream monitoring data has been separated from the rest of the water quality constituents and is located in its own filter box (to the right of "Water Quality Constituent(s)).  
  • Use the vertical menu bar in the upper right of the map to customize the map.
    • To view the full menu and descriptions of the icons, click on the Expand icon (double arrows) at the bottom of the vertical menu (the last icon).
    • To view the list of symbols and their meanings, click on the Legend icon (bullet points). 
    • To change the preset view, click on the Bookmarks icon (bookmark). 
    • To view the different map layers, click on the Layers icon (stacked boxes). Hidden layers will have crossed-out eye icons, whereas visible layers will not have an icon present. 
    • To change the basemap, click on the Basemap icon (four small squares) and select from the options.
  • To move around the map, click and hold the cursor on the map, then drag it to see different areas. To zoom in, double click on area of interest on the map. There are also Zoom in (plus symbol)/Zoom out icons (minus symbol) located at the bottom right of the map.
  • To reset the entire dashboard to its preset layers and features, including the map, click the Reset icon (circular arrow) located in the lower right-hand corner of the dashboard. 

How to use

The map and tables (dashboard) show all available data for all water quality constituents. To select the constituents discussed above, click on the "Biological & Stream Monitoring" filter and select the relevant one from the dropdown options. The dashboard should update automatically to show relevant monitoring stations (Station IDs). 

To explore the data using the map:

  1. Zoom in on a monitoring station and click on it.
  2. A pop up text box will appear showing a data summary for each constituent. 
  3. Use the left/right arrow icons at the top left of the pop up box to scroll through all records. Please note: Arrows are only present when the selected Station ID has data for more than one filtered constituent.
  4. To zoom in further on the station from the pop up box, click the magnifying glass icon in the top right corner (below the Station ID name). 
  5. Zooming in on the map will also filter the list of Station IDs in the table on the top right of the dashboard to show only those stations visible in the map extent.

To explore the data using the tables:

Select the "Biomonitoring" tab at the bottom of lower table.