The Rivanna River is doing just average, according to a recent health report card from the Rivanna Conservation Alliance.

The Rivanna Conservation Alliance, or RCA, is a nonprofit watershed organization created to help monitor, clean and protect the Rivanna River and its tributaries. It was formed in 2016 through a merger between the Rivanna Conservation Society and StreamWatch.

The report card, which compiles data from 2015 to 2020, graded the river based on the presence of E. coli bacteria and organisms in samples gathered from 50 sites throughout the river’s watershed. E. coli is considered dangerous and can cause disease in humans and other animals.

Weekly E. coli bacteria samples collected by RCA’s approximately 120 volunteer water quality throughout the period studied. Virginia’s water quality standard for E. coli is 410 bacteria colonies per 100mL of water. Streams meet the standard if at least 90 percent of water samples are lower than 410 MPN.

The watersheds were broken into five areas, with South Fork Rivanna subwatershed one and Lower Rivanna watershed each receiving a “B” ranking and the South Fork Rivanna subwatershed two, North Fork Rivanna watershed and Middle Rivanna watershed each receiving a “C” ranking. The “B” ranking indicates that streams scored 60.0 or higher, meeting Virginia’s water quality standard. This is the first time the river has been scored by the RCA.

The lower ranked watersheds are all clustered closer to Charlottesville and the more densely populated portions of the area.

According to Rachel Pence, manager of the monitoring program, each spring and fall volunteers head to the sites to catch, identify and count the different small organisms that inhabit the bottoms of rivers and streams.

Specifically, Pence said the organisms the RCA is looking for are called benthic macroinvertebrates — benthic meaning bottom dwelling, macro meaning that they can be observed with the naked eye and invertebrate meaning they have no backbone. That includes things like mayflies, stoneflies, caddisflies, crawfish, clams and snails, among other organisms, Pence said.

“Healthy streams have really well balanced populations that have a lot of different types of organisms living in it and they all have different pollution tolerance values, or they have different sensitivities, to different impairments to pollutants,” she said. “Some are more sensitive to things like low dissolved oxygen, high sediment loads, organic pollution, things like that, so the organisms that we find really tell us a story about how healthy or unhealthy a stream is.”

Stream health is important because it affects overall ecosystem health, Pence said, and organisms — specifically bugs — in streams are food for animals both in the water and on land.

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