​The Maryland Biological Stream Survey (MBSS) has collected biological, physical, and chemical data at sites within the Maryland Sentinel Site Network since 2000 (some sites as early as 1995). This network includes 30 minimally degraded stream sites located in four regions across the state (Eastern Coastal Plain, Western Coastal Plain, Eastern Piedmont, and Highlands). Monitoring of these sites allows MBSS to better understand natural conditions of Maryland streams by region and how these conditions vary annually. Data from these sites can also be used in comparison with degraded streams throughout the state to determine which annual differences are the result of natural variation versus those potentially resulting from anthropogenic influence.

Sentinel sites in Maryland's Eastern Coastal Plain region

Sentinel sites in Maryland's Western Coastal Plain region

Sentinel sites in Maryland's Eastern Piedmont region

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Sentinel sites in Maryland's Highlands region

• 2023 Sentinel Site Repor​t: Spatial and Temporal Trends in Biological, Physical, and Chemical Data (1995 – 2020) Collected at 30 Stream Sites within the Maryland Sentinel Site Network
  
• 2014 Sentinel Site Report: A Multi-Year Update (2011 – 2014) to Maryland Biological Stream Survey’s Sentinel Site Network
  
• 2010 Sentinel Site Report: Maryland Biological Stream Survey’s Sentinel Site Network: A Multi-purpose Monitoring Program