top of page

Benthic Macroinvertebrate Monitoring

Fast FAQs

Started in: 2010

Protocol measures: Number and species of aquatic insect larva that live in the water

Number of volunteers that run the program: 70

Number of sites monitored: 9

Where the data is sent:  Virginia Save Our Streams, a part of the Izaac Walton League of America

As stewards of the Middle River and its tributaries we need ways to measure the quality and health of these water bodies. Quantitatively, we can measure bacteria like E. coli, nutrient and chemical pollutants, and physical attributes like temperature, sediment, and oxygenation. All of these measures provide a valuable snapshot of water quality at the time of the assessment.


To gauge the ongoing water quality of the river throughout the year, however, we turn to benthic monitoring which focuses on organisms that are present in the river every day. Benthic invertebrates (i.e. bottom-dwelling spineless critters) are responsive to environmental change and are excellent indicators of system stresses. Benthic assessment protocols are the method of choice for gauging the biotic integrity of streams. 


Many of these stream-dwelling critters are extremely sensitive to any type of pollution so that by knowing the types and numbers of these populations we are able to determine stream water quality.  The bottom-dwelling macroinvertebrates make up the base of the food chain for all stream inhabitants and are essential to stream habitat. Monitoring is carried out twice a year by trained monitors in teams of two to three citizen scientists who capture, count and identify all the critters in a given space.  The counts of specific types of organisms, both tolerant and intolerant of stream pollution, are plugged into an algorithm that gives a score between 0 to 12 (with 12 being the "best" score.) To date, we have a 10-year database of stream health of around nine different sites that have been monitored by over 70 volunteers.

bottom of page