What is Probabilistic Monitoring?

ProbMon Handouts

ProbMon Reports

ProbMon Presentations

ProbMon Posters

What is Probabilistic Monitoring?

Probabilistic monitoring (ProbMon) is the sampling of randomly selected stations. These monitoring stations are generated by a computer program that randomly chooses monitoring sites on rivers and streams throughout Virginia. Water quality monitoring stations in Virginia are typically located at bridges. These monitoring stations are known as targeted monitoring sites.

Targeted monitoring has utility for monitoring regulatory compliance of pollution sources, identifying impaired waters, and for tracking local pollution events. However, it is not appropriate to extrapolate results from targeted stations to unsampled watersheds over large geographic areas. Data to answer such questions are best obtained from sample locations chosen so that all streams have an equal chance of being sampled. Consequently, to answer the question "How good is the water quality in Virginia?", a new more comprehensive data set was needed.

In order to address statewide and regional questions about water quality, the Virginia Department of Environmental of Quality (VDEQ) added probabilistic monitoring networks to its estuarine monitoring program in 2000 and its freshwater monitoring program in 2001. This website focuses on the freshwater program. The aim of ProbMon is to provide accurate statewide and regional assessments of the chemical, physical, and biological conditions of Virginia's freshwater resources.

ProbMon Handouts

• Virginia's Freshwater Probabilistic Monitoring Program

ProbMon Reports

• 2012 Integrated Report Freshwater Probabilistic Monitoring Chapter
• 2010 Integrated Report Freshwater Probabilistic Monitoring Chapter
• 2008 Integrated Report Freshwater Probabilistic Monitoring Chapter
• Using Probabilistic Monitoring Data to Validate the Non-Coastal Virginia Stream Condition Index
• 2004 Virginia Water Research Symposium - Probabilistic Monitoring Report
• Probabilistic Monitoring Section in the 2002 305(b) Report
• 2001 Probabilistic Monitoring Report

ProbMon Presentations

• Preliminary Findings of using Fish Community Data to Determine Biological Health in Virginia Streams and Rivers (2011)
• Using Probabilistic Data to Validate the Non-Coastal Virginia Stream Condition Index (2006)
• Probabilistic Monitoring in Virginia: Experiences from the First Five Years (2006)
• Probabilistic Monitoring Presentation at the 2004 EPA EMAP Conference
• Probabilistic Monitoring Presentation at the 2002 EPA Cacapon Workshop

ProbMon Posters

• Assessing the Relationship between Habitat and Biological Communities Using Relative Bed Stability (2007)
• The Occurrence and Geospatial Distribution of Toxic Organic Contaminants in a Statewide Stratum (2005)
• Fundamentals of the Use of Performance Reference Compounds (PRCs) in Passive Samplers (2005)
• Use of Semipermeable Membrane Devices (SPMDs) in a Probabilistic Assessment of Virginia Rivers (2005)
• Associations between Biological Metrics, Physical Habitat and Water Chemistry in Virginia's Mountain Ecoregions (2005)
• Ecoregional Assessment of Water Quality in Virginia's Non-Tidal Streams (2003)
• Probabilistic Monitoring Poster for 2001